Merck & Co. (MRK) 10-Q 9 Aug 21 2021 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Jun. 30, 2021	Jul. 31, 2021
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2021
Document Transition Report	false
Entity File Number	1-6571
Entity Registrant Name	Merck & Co., Inc.
Entity Incorporation, State or Country Code	NJ
Entity Tax Identification Number	22-1918501
Entity Address, Address Line One	2000 Galloping Hill Road
Entity Address, City or Town	Kenilworth
Entity Address, State or Province	NJ
Entity Address, Postal Zip Code	07033
City Area Code	(908)
Local Phone Number	740-4000
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		2,531,374,696
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Entity Central Index Key	0000310158
Current Fiscal Year End Date	--12-31
Common Stock
Entity Information [Line Items]
Title of 12(b) Security	Common Stock ($0.50 par value)
Trading Symbol	MRK
Security Exchange Name	NYSE
1.125% Notes due 2021
Entity Information [Line Items]
Title of 12(b) Security	1.125% Notes due 2021
Trading Symbol	MRK/21
Security Exchange Name	NYSE
0.500% Notes due 2024
Entity Information [Line Items]
Title of 12(b) Security	0.500% Notes due 2024
Trading Symbol	MRK 24
Security Exchange Name	NYSE
1.875% Notes due 2026
Entity Information [Line Items]
Title of 12(b) Security	1.875% Notes due 2026
Trading Symbol	MRK/26
Security Exchange Name	NYSE
2.500% Notes due 2034
Entity Information [Line Items]
Title of 12(b) Security	2.500% Notes due 2034
Trading Symbol	MRK/34
Security Exchange Name	NYSE
1.375% Notes due 2036
Entity Information [Line Items]
Title of 12(b) Security	1.375% Notes due 2036
Trading Symbol	MRK 36A
Security Exchange Name	NYSE

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENT OF INCOME - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Sales	$ 11,402	$ 9,353	$ 22,029	$ 19,641
Costs, Expenses and Other
Cost of sales	3,104	2,747	6,303	5,576
Selling, general and administrative	2,281	2,085	4,468	4,276
Research and development	4,321	2,085	6,732	4,260
Restructuring costs	82	82	380	152
Other (income) expense, net	(103)	(387)	(558)	(325)
Total Costs, Expenses and Other	9,685	6,612	17,325	13,939
Income from Continuing Operations Before Taxes	1,717	2,741	4,704	5,702
Taxes on Income from Continuing Operations	503	396	741	891
Net Income from Continuing Operations	1,214	2,345	3,963	4,811
Less: Net Income (Loss) Attributable to Noncontrolling Interests	1	4	5	(1)
Net Income from Continuing Operations Attributable to Merck & Co., Inc.	1,213	2,341	3,958	4,812
Income from Discontinued Operations, Net of Taxes and Amounts Attributable to Noncontrolling Interests	332	661	766	1,409
Net Income Attributable to Merck & Co. Inc.	$ 1,545	$ 3,002	$ 4,724	$ 6,221
Basic Earnings per Common Share Attributable to Merck & Co., Inc. Common Shareholders:
Income from Continuing Operations	$ 0.48	$ 0.93	$ 1.56	$ 1.90
Income from Discontinued Operations	0.13	0.26	0.30	0.56
Net Income	0.61	1.19	1.87	2.46
Earnings per Common Share Assuming Dilution Attributable to Merck & Co., Inc. Common Shareholders:
Income from Continuing Operations	0.48	0.92	1.56	1.89
Income from Discontinued Operations	0.13	0.26	0.30	0.55
Net Income	$ 0.61	$ 1.18	$ 1.86	$ 2.45

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net Income Attributable to Merck & Co., Inc.	$ 1,545	$ 3,002	$ 4,724	$ 6,221
Other Comprehensive Income (Loss) Net of Taxes:
Net unrealized gain (loss) on derivatives, net of reclassifications	10	(120)	240	(16)
Net unrealized loss on investments, net of reclassifications	0	0	0	(18)
Benefit plan net gain and prior service credit, net of amortization	1,403	39	1,484	99
Cumulative translation adjustment	132	79	(167)	(265)
Other comprehensive income (loss), net of taxes	1,545	(2)	1,557	(200)
Comprehensive Income Attributable to Merck & Co., Inc.	$ 3,090	$ 3,000	$ 6,281	$ 6,021

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEET - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Current Assets
Cash and cash equivalents	$ 8,575	$ 8,050
Accounts receivable (net of allowance for doubtful accounts of $72 in 2021 and $67 in 2020)	7,843	6,803
Inventories (excludes inventories of $2,412 in 2021 and $2,070 in 2020 classified in Other assets - see Note 7)	5,499	5,554
Other current assets	6,748	4,674
Current assets of discontinued operations	0	2,683
Total current assets	28,665	27,764
Investments	411	785
Property, Plant and Equipment, at cost, net of accumulated depreciation of $18,236 in 2021 and $18,162 in 2020	18,064	17,000
Goodwill	18,873	18,882
Other Intangibles, Net	13,622	14,101
Other Assets	11,053	9,881
Noncurrent Assets of Discontinued Operations	0	3,175
Total Assets	90,688	91,588
Current Liabilities
Loans payable and current portion of long-term debt	2,488	6,431
Trade accounts payable	3,897	4,327
Accrued and other current liabilities	12,888	12,212
Income taxes payable	971	1,597
Dividends payable	1,662	1,674
Current liabilities of discontinued operations	0	1,086
Total current liabilities	21,906	27,327
Long-Term Debt	24,033	25,360
Deferred Income Taxes	1,489	1,005
Other Noncurrent Liabilities	9,872	12,306
Noncurrent Liabilities of Discontinued Operations	0	186
Merck & Co., Inc. Stockholders’ Equity
Common stock, $0.50 par value Authorized - 6,500,000,000 shares Issued - 3,577,103,522 shares in 2021 and 2020	1,788	1,788
Other paid-in capital	44,039	39,588
Retained earnings	48,777	47,362
Accumulated other comprehensive loss	(4,628)	(6,634)
Stockholders' equity before deduction for treasury stock	89,976	82,104
Less treasury stock, at cost: 1,044,351,147 shares in 2021 and 1,046,877,695 shares in 2020	56,682	56,787
Total Merck & Co., Inc. stockholders’ equity	33,294	25,317
Noncontrolling Interests	94	87
Total equity	33,388	25,404
Liabilities and Equity	$ 90,688	$ 91,588

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEET (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 72	$ 67
Inventories classified in Other assets	2,412	2,070
Accumulated depreciation	$ 18,236	$ 18,162
Common stock, par value (in dollars per share)	$ 0.50	$ 0.50
Common stock, shares authorized (shares)	6,500,000,000	6,500,000,000
Common stock, shares issued (in shares)	3,577,103,522	3,577,103,522
Treasury Stock, Shares	1,044,351,147	1,046,877,695

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash Flows from Operating Activities
Net income from continuing operations	$ 3,963	$ 4,811
Adjustments to reconcile net income from continuing operations to net cash provided by operating activities:
Amortization	871	988
Depreciation	749	808
Intangible asset impairment charges	0	20
Charge for the acquisition of Pandion Therapeutics, Inc.	1,556	0
Deferred income taxes	29	101
Share-based compensation	243	213
Other	(526)	(204)
Net changes in assets and liabilities	(3,655)	(4,112)
Net Cash Provided by Operating Activities from Continuing Operations	3,230	2,625
Cash Flows from Investing Activities
Capital expenditures	(2,068)	(1,553)
Purchases of securities and other investments	(1)	(77)
Proceeds from sales of securities and other investments	386	1,892
Acquisition of Pandion Therapeutics, Inc. net of cash acquired	(1,554)	0
Acquisition of ArQule, Inc., net of cash acquired	0	(2,545)
Other acquisitions, net of cash acquired	(90)	(321)
Other	16	194
Net Cash Used in Investing Activities from Continuing Operations	(3,311)	(2,410)
Cash Flows from Financing Activities
Net change in short-term borrowings	(3,983)	1,967
Payments on debt	(1,153)	(1,952)
Distribution from Organon & Co.	9,000	0
Proceeds from issuance of debt	0	4,445
Purchases of treasury stock	(239)	(1,281)
Dividends paid to stockholders	(3,318)	(3,128)
Proceeds from exercise of stock options	51	40
Other	(194)	(444)
Net Cash Provided by (Used in) Financing Activities from Continuing Operations	164	(353)
Discontinued Operations
Net cash provided by operating activities	1,051	1,449
Net cash used in investing activities	(134)	(100)
Net cash used in financing activities	(504)	0
Net Cash Flows Provided by Discontinued Operations	413	1,349
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	(19)	2
Net Increase in Cash, Cash Equivalents and Restricted Cash	477	1,213
Cash, Cash Equivalents and Restricted Cash at Beginning of Year (includes restricted cash of $103 at January 1, 2021 included in Other Assets)	8,153	9,934
Cash, Cash Equivalents and Restricted Cash at End of Period (includes restricted cash of $55 at June 30, 2021 included in Other Assets)	$ 8,630	$ 11,147

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Statement of Cash Flows [Abstract]
Restricted cash	$ 55	$ 103

Basis of Presentation

Basis of Presentation	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements of Merck & Co., Inc. (Merck or the Company) have been prepared pursuant to the rules and regulations for reporting on Form 10-Q. Accordingly, certain information and disclosures required by accounting principles generally accepted in the United States (U.S.) (GAAP) for complete consolidated financial statements are not included herein. These interim statements should be read in conjunction with the audited financial statements and notes thereto included in Merck’s Form 10-K filed on February 25, 2021. The results of operations of any interim period are not necessarily indicative of the results of operations for the full year. In the Company’s opinion, all adjustments necessary for a fair statement of these interim statements have been included and are of a normal and recurring nature. Spin-Off of Organon & Co. On June 2, 2021, Merck completed the spin-off of products from its women’s health, biosimilars and established brands businesses into a new, independent, publicly traded company named Organon & Co. (Organon) through a distribution of Organon’s publicly traded stock to Company shareholders. The established brands included in the transaction consisted of dermatology, non-opioid pain management, respiratory, select cardiovascular products, as well as the rest of Merck’s diversified brands franchise. Merck’s existing research pipeline programs will continue to be owned and developed within Merck as planned. The historical results of the women’s health, biosimilars and established brands businesses that were contributed to Organon in the spin-off have been reflected as discontinued operations in the Company’s consolidated financial statements through the date of the spin-off (see Note 2). Recently Adopted Accounting Standards In December 2019, the Financial Accounting Standards Board (FASB) issued amended guidance on the accounting and reporting of income taxes. The guidance is intended to simplify the accounting for income taxes by removing exceptions related to certain intraperiod tax allocations and deferred tax liabilities, clarifying guidance primarily related to evaluating the step-up tax basis for goodwill in a business combination, and reflecting enacted changes in tax laws or rates in the annual effective tax rate. The Company adopted the new guidance effective January 1, 2021. There was no impact to the Company’s consolidated financial statements upon adoption. In January 2020, the FASB issued new guidance intended to clarify certain interactions between accounting standards related to equity securities, equity method investments and certain derivatives. The guidance addresses accounting for the transition into and out of the equity method of accounting and measuring certain purchased options and forward contracts to acquire investments. The Company adopted the new guidance effective January 1, 2021. There was no impact to the Company’s consolidated financial statements upon adoption. Recently Issued Accounting Standard Not Yet Adopted In March 2020, the FASB issued optional guidance to ease the potential burden in accounting for (or recognizing the effects of) reference rate reform on financial reporting and subsequently issued clarifying amendments. The guidance provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships, and other transactions that reference the London Interbank Offered Rate (LIBOR) or another reference rate expected to be discontinued because of reference rate reform. The optional guidance is effective upon issuance and can be applied on a prospective basis at any time between January 1, 2020 through December 31, 2022. The Company is currently evaluating the impact of adoption on its consolidated financial statements.

Spin-Off of Organon & Co.

Spin-Off of Organon & Co.	Jun. 02, 2021
Discontinued Operations and Disposal Groups [Abstract]
Spin-Off of Organon & Co.	Spin-Off of Organon & Co. On June 2, 2021, Merck completed the spin-off of Organon through a distribution of Organon’s publicly traded stock to Company shareholders. In connection with the spin-off, each Merck shareholder received one tenth of a share of Organon’s common stock for each share of Merck common stock held by such shareholder. The distribution is expected to qualify as tax free to Merck and its shareholders for U.S. federal income tax purposes. Indebtedness of $9.5 billion principal amount, consisting of term loans and senior notes, was issued in 2021 in connection with the spin-off and assumed by Organon. Merck is no longer the obligor of any Organon debt or financing arrangements. Cash proceeds of $9.0 billion were distributed by Organon to Merck in connection with the spin-off. Also in connection with the spin-off, Merck and Organon entered into a separation and distribution agreement and also entered into various other agreements to effect the spin-off and provide a framework for the relationship between Merck and Organon after the spin-off, including a transition services agreement (TSA), manufacturing and supply agreements (MSAs), trademark license agreements, intellectual property license agreements, an employee matters agreement, a tax matters agreement and certain other commercial agreements. Under the TSA, Merck will provide Organon various services and, similarly, Organon will provide Merck various services. The provision of services under the TSA agreement generally will terminate within 25 months following the spin-off. Merck and Organon also entered into a series of interim operating agreements pursuant to which in various jurisdictions where Merck held licenses, permits and other rights in connection with marketing, import and/or distribution of Organon products prior to the separation, Merck will continue to market, import and distribute such products until such time as the relevant licenses and permits are transferred to Organon. Under such interim operating agreements and in accordance with the separation and distribution agreement, Merck will continue operations in the affected markets on behalf of Organon, with Organon receiving all of the economic benefits and burdens of such activities. Additionally, Merck and Organon entered into a number of MSAs pursuant to which Merck will (a) manufacture and supply certain active pharmaceutical ingredients for Organon, (b) toll manufacture and supply certain formulated pharmaceutical products for Organon, and (c) package and label certain finished pharmaceutical products for Organon. Similarly, Organon and Merck entered into a number of MSAs pursuant to which Organon will (a) manufacture and supply certain formulated pharmaceutical products for Merck, and (b) package and label certain finished pharmaceutical products for Merck. The terms of the MSAs range in initial duration from four years to ten years. Amounts included in the condensed consolidated statement of income for the above agreements were immaterial in the second quarter of 2021. The amount due from Organon under the above agreements was $1.6 billion at June 30, 2021 and is reflected in Other current assets . The amount due to Organon under these agreements was $1.0 billion at June 30, 2021 and is included in A ccrued and other current liabilities . The results of the women’s health, biosimilars and established brands businesses (previously included in the Pharmaceutical segment) that were contributed to Organon in the spin-off, as well as interest expense related to the debt issuance in 2021, have been reflected as discontinued operations in the Company’s condensed consolidated statement of income as Income from Discontinued Operations, Net of Taxes and Amounts Attributable to Noncontrolling Interests through June 2, 2021, the date of the spin-off. Prior periods have been recast to reflect this presentation. As a result of the spin-off of Organon, Merck incurred separation costs of $307 million and $556 million in the three and six months ended June 30, 2021, respectively, and $120 million and $290 million in the three and six months ended June 30, 2020, respectively, which are also included in Income from Discontinued Operations, Net of Taxes and Amounts Attributable to Noncontrolling Interests . These costs primarily relate to professional fees for separation activities within finance, tax, legal and information technology system functions, as well as investment banking fees. As of December 31, 2020, the assets and liabilities associated with these businesses are classified as assets and liabilities of discontinued operations in the condensed consolidated balance sheet. Details of Income from discontinued operations, net of taxes and amounts attributable to noncontrolling interests are as follows: Three Months Ended Six Months Ended ($ in millions) 2021 (1) 2020 2021 (1) 2020 Sales $ 1,059 $ 1,519 $ 2,512 $ 3,288 Costs, Expenses and Other Cost of sales 318 412 789 895 Selling, general and administrative 431 293 877 657 Research and development 50 38 103 72 Restructuring costs — 1 1 3 Other (income) expense, net (23) (4) (15) 4 776 740 1,755 1,631 Income from discontinued operations before taxes 283 779 757 1,657 Tax (benefit) provision (49) 114 (12) 239 Income from discontinued operations, net of taxes 332 665 769 1,418 Less: Income of discontinued operations attributable to noncontrolling interests — 4 3 9 Income from discontinued operations, net of taxes and amounts attributable to noncontrolling interests $ 332 $ 661 $ 766 $ 1,409 (1) Reflects amounts through the June 2, 2021 spin-off date. Details of assets and liabilities of discontinued operations are as follows: ($ in millions) December 31, 2020 Cash and cash equivalents $ 12 Accounts receivable, less allowance for doubtful accounts 1,048 Inventories 756 Other current assets 867 Current assets of discontinued operations $ 2,683 Property, plant and equipment, net $ 986 Goodwill 1,356 Other intangibles, net 503 Other assets 330 Noncurrent Assets of Discontinued Operations $ 3,175 Trade accounts payable $ 267 Accrued and other current liabilities 841 Income taxes payable (22) Total current liabilities of discontinued operations $ 1,086 Deferred income taxes $ 10 Other noncurrent liabilities 176 Noncurrent Liabilities of Discontinued Operations $ 186 As a result of the spin-off of Organon, Merck distributed net liabilities of $5.1 billion as of June 2, 2021 consisting of debt of $9.4 billion (described above), goodwill of $1.4 billion, property, plant and equipment of $981 million, cash of $929 million, inventory of $815 million, other intangibles, net, of $519 million and other net liabilities of $328 million. The spin-off also resulted in a net decrease to Accumulated other comprehensive loss of $449 million consisting of $421 million for the derecognition of net losses on foreign currency translation adjustments and $28 million associated with employee benefit plans. The distribution of the net liabilities and reduction to Accumulated other comprehensive loss resulted in a net $4.6 billion increase to Other paid-in capital . The Company has share-based compensation plans under which the Company grants restricted stock units (RSUs) and performance share units (PSUs) to certain management level employees. In addition, employees and non-employee directors were granted options to purchase shares of Company common stock at the fair market value at the time of grant. In connection with the spin-off of Organon, all outstanding Merck stock options, RSUs and PSUs (whether vested or unvested) were converted into adjusted Merck awards for current and former Merck employees or Organon awards for Organon employees. Such adjusted awards preserved the same intrinsic value and general terms and conditions (including vesting) as were in place immediately prior to the adjustments. Approximately 1.3 million RSUs, 1.9 million stock options and 248 thousand PSUs were converted from Merck awards into Organon awards.

Acquisitions, Research Collabor

Acquisitions, Research Collaborations and License Agreements	6 Months Ended
	Jun. 30, 2021
Business Combinations [Abstract]
Acquisitions, Research Collaborations and License Agreements	Acquisitions, Research Collaborations and License Agreements The Company continues to pursue acquisitions and the establishment of external alliances such as research collaborations and licensing agreements to complement its internal research capabilities. These arrangements often include upfront payments, as well as expense reimbursements or payments to the third party, and milestone, royalty or profit share arrangements, contingent upon the occurrence of certain future events linked to the success of the asset in development. The Company also reviews its marketed products and pipeline to examine candidates which may provide more value through out-licensing and, as part of its portfolio assessment process, may also divest certain assets. Pro forma financial information for acquired businesses is not presented if the historical financial results of the acquired entity are not significant when compared with the Company’s financial results. In April 2021, Merck acquired Pandion Therapeutics, Inc. (Pandion), a clinical-stage biotechnology company developing novel therapeutics designed to address the unmet needs of patients living with autoimmune diseases. Pandion is advancing a pipeline of precision immune modulators targeting critical immune control nodes. Total consideration paid of $1.9 billion included $147 million of transaction costs primarily comprised of share-based compensation payments to settle equity awards. The transaction was accounted for as an acquisition of an asset. Merck recorded net assets of $156 million (primarily cash) and Research and development expenses of $1.7 billion in the second quarter and first six months of 2021 related to the transaction. There are no future contingent payments associated with the acquisition. In March 2021, Merck and Gilead Sciences, Inc. (Gilead) entered into an agreement to jointly develop and commercialize long-acting treatments in HIV that combine Merck’s investigational nucleoside reverse transcriptase translocation inhibitor, islatravir, and Gilead’s investigational capsid inhibitor, lenacapavir. The collaboration will initially focus on long-acting oral formulations and long-acting injectable formulations of these combination products, with other formulations potentially added to the collaboration as mutually agreed. There was no upfront payment made by either party upon entering into the agreement. Under the terms of the agreement, Gilead and Merck will share operational responsibilities, as well as development, commercialization and marketing costs, and any future revenues. Global development and commercialization costs will be shared 60% Gilead and 40% Merck across the oral and injectable formulation programs. For long-acting oral products, Gilead will lead commercialization in the U.S. and Merck will lead commercialization in the EU and the rest of the world. For long-acting injectable products, Merck will lead commercialization in the U.S. and Gilead will lead commercialization in the EU and the rest of the world. Gilead and Merck will co-promote in the U.S. and certain other major markets. Merck and Gilead will share global product revenues equally until product revenues surpass certain pre-agreed per formulation revenue tiers. Upon passing $2.0 billion a year in net product sales for the oral combination, the revenue split will adjust to 65% Gilead and 35% Merck for any revenues above the threshold. Upon passing $3.5 billion a year in net product sales for the injectable combination, the revenue split will adjust to 65% Gilead and 35% Merck for any revenues above the threshold. Beyond the potential combinations of investigational lenacapavir and investigational islatravir, Gilead will have the option to license certain of Merck’s investigational oral integrase inhibitors to develop in combination with lenacapavir. Reciprocally, Merck will have the option to license certain of Gilead’s investigational oral integrase inhibitors to develop in combination with islatravir. Each company may exercise its option for an investigational oral integrase inhibitor of the other company following completion of the first Phase 1 clinical trial of that integrase inhibitor. Upon exercise of an option, the companies will split development costs and revenues, unless the non-exercising company decides to opt-out. In January 2021, Merck entered into an exclusive license and research collaboration agreement with Artiva Biotherapeutics, Inc. (Artiva) to discover, develop and manufacture CAR-NK cells that target certain solid tumors using Artiva’s proprietary platform. Merck and Artiva agreed to engage in up to three different research programs, each covering a collaboration target. Merck has sole responsibility for all development and commercialization activities (including regulatory filing and approval). Under the terms of the agreement, Merck made an upfront payment of $30 million, which was included in Research and development expenses in the first six months of 2021, for license and other rights for the first two collaboration targets and agreed to make another upfront payment of $15 million for license and other rights for the third collaboration target when it is selected by Merck and accepted by Artiva. In addition, Artiva is eligible to receive future contingent milestone payments (which span all three collaboration targets), aggregating up to: $217.5 million in developmental milestones, $570 million in regulatory milestones, and $1.05 billion in sales-based milestones. The agreement also provides for Merck to pay tiered royalties ranging from 7% to 14% on future sales. In December 2020, Merck acquired OncoImmune, a privately held, clinical-stage biopharmaceutical company, for an upfront payment of $423 million. OncoImmune’s lead therapeutic candidate MK-7110 (formerly known as CD24Fc) was being evaluated for the treatment of patients hospitalized with coronavirus disease 2019 (COVID-19). The transaction was accounted for as an acquisition of an asset. Under the agreement, prior to the completion of the acquisition, OncoImmune spun-out certain rights and assets unrelated to the MK-7110 program to a new entity owned by the existing shareholders of OncoImmune. In connection with the closing of the acquisition, Merck invested $50 million for a 20% ownership interest in the new entity, which was valued at $33 million resulting in a $17 million premium. Merck also recognized other net liabilities of $22 million. The Company recorded Research and development expenses of $462 million in 2020 related to this transaction. In 2021, Merck received feedback from the U.S. Food and Drug Administration (FDA) that additional data would be needed to support a potential Emergency Use Authorization application and therefore the Company did not expect MK-7110 would become available until the first half of 2022. Given this timeline and the technical, clinical and regulatory uncertainties, the availability of a number of medicines for patients hospitalized with COVID-19, and the need to concentrate Merck’s resources on accelerating the development and manufacture of the most viable therapeutics and vaccines, Merck decided to discontinue development of MK-7110 for the treatment of COVID-19. Due to the discontinuation, the Company recorded charges of $37 million and $207 million in the second quarter and first six months of 2021, respectively, which are reflected in Cost of sales and relate to fixed-asset and materials write-offs, as well as the recognition of liabilities for purchase commitments . In June 2020, Merck acquired privately held Themis Bioscience GmbH (Themis), a company focused on vaccines (including a COVID-19 vaccine candidate, V591) and immune-modulation therapies for infectious diseases and cancer for $366 million. The acquisition originally provided for Merck to make additional contingent payments of up to $740 million. The transaction was accounted for as an acquisition of a business. The Company determined the fair value of the contingent consideration was $85 million at the acquisition date utilizing a probability-weighted estimated cash flow stream using an appropriate discount rate dependent on the nature and timing of the milestone payments. Merck recognized intangible assets for in-process research and development (IPR&D) of $113 million, cash of $59 million, deferred tax assets of $72 million and other net liabilities of $32 million. The excess of the consideration transferred over the fair value of net assets acquired of $239 million was recorded as goodwill that was allocated to the Pharmaceutical segment and is not deductible for tax purposes. The fair values of the identifiable intangible assets related to IPR&D were determined using an income approach. Actual cash flows are likely to be different than those assumed. In January 2021, the Company announced it was discontinuing development of V591. As a result, in 2020, the Company recorded an IPR&D impairment charge of $90 million within Research and development expenses. The Company also recorded a reduction in Research and development expenses resulting from a decrease in the related liability for contingent consideration of $45 million since future contingent milestone payments have been reduced to $450 million in the aggregate, including up to $60 million for development milestones, up to $196 million for regulatory approval milestones, and up to $194 million for commercial milestones. In January 2020, Merck acquired ArQule, Inc. (ArQule), a publicly traded biopharmaceutical company focused on kinase inhibitor discovery and development for the treatment of patients with cancer and other diseases. Total consideration paid of $2.7 billion included $138 million of share-based compensation payments to settle equity awards attributable to precombination service and cash paid for transaction costs on behalf of ArQule. The Company incurred $95 million of transaction costs directly related to the acquisition of ArQule, consisting almost entirely of share-based compensation payments to settle non-vested equity awards attributable to postcombination service. These costs were included in Selling, general and administrative expenses in the first six months of 2020. ArQule’s lead investigational candidate, MK-1026 (formerly known as ARQ 531), is a novel, oral Bruton’s tyrosine kinase (BTK) inhibitor currently being evaluated for the treatment of B-cell malignancies. The transaction was accounted for as an acquisition of a business. The estimated fair value of assets acquired and liabilities assumed from ArQule is as follows: ($ in millions) January 16, 2020 Cash and cash equivalents $ 145 IPR&D MK-1026 (formerly ARQ 531) (1) 2,280 Licensing arrangement for ARQ 087 80 Deferred income tax liabilities (361) Other assets and liabilities, net 34 Total identifiable net assets 2,178 Goodwill (2) 512 Consideration transferred $ 2,690 (1) The estimated fair value of the identifiable intangible asset related to IPR&D was determined using an income approach. The future net cash flows were discounted to present value utilizing a discount rate of 12.5%. Actual cash flows are likely to be different than those assumed. (2) The goodwill was allocated to the Pharmaceutical segment and is not deductible for tax purposes.

Collaborative Arrangements

Collaborative Arrangements	6 Months Ended
	Jun. 30, 2021
Collaborative Arrangements [Abstract]
Collaborative Arrangements	Collaborative Arrangements Merck has entered into collaborative arrangements that provide the Company with varying rights to develop, produce and market products together with its collaborative partners. Both parties in these arrangements are active participants and exposed to significant risks and rewards dependent on the commercial success of the activities of the collaboration. Merck’s more significant collaborative arrangements are discussed below. For further details refer to Note 4 to the consolidated financial statements included in Merck’s 2020 Form 10‑K. AstraZeneca In 2017, Merck and AstraZeneca PLC (AstraZeneca) entered into a global strategic oncology collaboration to co-develop and co-commercialize AstraZeneca’s Lynparza (olaparib) for multiple cancer types. Independently, Merck and AstraZeneca will develop and commercialize Lynparza in combinations with their respective PD-1 and PD-L1 medicines, Keytruda and Imfinzi. The companies are also jointly developing and commercializing AstraZeneca’s Koselugo (selumetinib) for multiple indications. Under the terms of the agreement, AstraZeneca and Merck will share the development and commercialization costs for Lynparza and Koselugo monotherapy and non-PD-L1/PD-1 combination therapy opportunities. Profits from Lynparza and Koselugo product sales generated through monotherapies or combination therapies are shared equally. AstraZeneca is the principal on Lynparza and Koselugo sales transactions. Merck records its share of Lynparza and Koselugo product sales, net of cost of sales and commercialization costs, as alliance revenue and its share of development costs associated with the collaboration as part of Research and development expenses. Reimbursements received from AstraZeneca for research and development expenses are recognized as reductions to Research and development costs. As part of the agreement, Merck made an upfront payment to AstraZeneca and also made payments over a multi-year period for certain license options. In addition, the agreement provides for additional contingent payments from Merck to AstraZeneca related to the successful achievement of sales-based and regulatory milestones. As of June 30, 2021, sales-based milestone payments accrued but not yet paid totaled $400 million. Potential future sales-based milestone payments of $2.7 billion have not yet been accrued as they are not deemed by the Company to be probable at this time. Additionally, potential future regulatory milestone payments of $1.4 billion remain under the agreement. The intangible asset balance related to Lynparza (which includes capitalized sales-based and regulatory milestone payments) was $1.2 billion at June 30, 2021 and is included in Other Intangibles, Net . The amount is being amortized over its estimated useful life through 2028 as supported by projected future cash flows, subject to impairment testing. Summarized financial information related to this collaboration is as follows: Three Months Ended Six Months Ended ($ in millions) 2021 2020 2021 2020 Alliance revenue - Lynparza $ 248 $ 178 $ 475 $ 323 Alliance revenue - Koselugo 8 — 14 — Total alliance revenue $ 256 $ 178 $ 489 $ 323 Cost of sales (1) 42 137 84 164 Selling, general and administrative 43 39 83 72 Research and development 31 37 60 73 ($ in millions) June 30, 2021 December 31, 2020 Receivables from AstraZeneca included in Other current assets $ 258 $ 215 Payables to AstraZeneca included in Accrued and other current liabilities (2) 418 423 (1) Represents amortization of capitalized milestone payments. (2) Includes accrued milestone payments. Eisai In 2018, Merck and Eisai Co., Ltd. (Eisai) announced a strategic collaboration for the worldwide co-development and co-commercialization of Lenvima (lenvatinib), an orally available tyrosine kinase inhibitor discovered by Eisai. Under the agreement, Merck and Eisai will develop and commercialize Lenvima jointly, both as monotherapy and in combination with Keytruda . Eisai records Lenvima product sales globally (Eisai is the principal on Lenvima sales transactions), and Merck and Eisai share applicable profits equally. Merck records its share of Lenvima product sales, net of cost of sales and commercialization costs, as alliance revenue. Expenses incurred during co-development are shared by the two companies in accordance with the collaboration agreement and reflected in Research and development expenses. Certain expenses incurred solely by Merck or Eisai are not shareable under the collaboration agreement, including costs incurred in excess of agreed upon caps and costs related to certain combination studies of Keytruda and Lenvima. Under the agreement, Merck made an upfront payment to Eisai and also made payments over a multi-year period for certain options rights (of which the final $125 million option payment was made in March 2021). In addition, the agreement provides for additional contingent payments from Merck to Eisai related to the successful achievement of sales-based and regulatory milestones. Merck made sales-based milestone payments of $200 million to Eisai in the first six months of 2021. As of June 30, 2021, sales-based milestone payments accrued but not yet paid totaled $600 million. Potential future sales-based milestone payments of $2.6 billion have not yet been accrued as they are not deemed by the Company to be probable at this time. Additionally, potential future regulatory milestone payments of $125 million remain under the agreement. The intangible asset balance related to Lenvima (which includes capitalized sales-based and regulatory milestone payments) was $1.0 billion at June 30, 2021 and is included in Other Intangibles, Net . The amount is being amortized over its estimated useful life through 2026 as supported by projected future cash flows, subject to impairment testing. Summarized financial information related to this collaboration is as follows: Three Months Ended Six Months Ended ($ in millions) 2021 2020 2021 2020 Alliance revenue - Lenvima $ 181 $ 151 $ 310 $ 279 Cost of sales (1) 47 135 94 170 Selling, general and administrative 31 19 54 31 Research and development 57 56 121 120 ($ in millions) June 30, 2021 December 31, 2020 Receivables from Eisai included in Other current assets $ 212 $ 157 Payables to Eisai included in Accrued and other current liabilities (2) 600 335 Payables to Eisai included in Other Noncurrent Liabilities (3) — 600 (1) Represents amortization of capitalized milestone payments. (2) Includes accrued milestone and future option payments. (3) Includes accrued milestone payments. Bayer AG In 2014, the Company entered into a worldwide clinical development collaboration with Bayer AG (Bayer) to market and develop soluble guanylate cyclase (sGC) modulators including Bayer’s Adempas (riociguat). The two companies have implemented a joint development and commercialization strategy. The collaboration also includes clinical development of Bayer’s Verquvo (vericiguat), which was approved in the U.S. in January 2021, in Japan in June 2021 and in the EU in July 2021. Under the agreement, Bayer commercializes Adempas in the Americas, while Merck commercializes in the rest of the world. For Verquvo, Merck commercializes in the U.S. and Bayer commercializes in the rest of the world. Both companies share in development costs and profits on sales. Merck records sales of Adempas and Verquvo in its marketing territories, as well as alliance revenue. Alliance revenue represents Merck’s share of profits from sales in Bayer’s marketing territories, which are product sales net of cost of sales and commercialization costs. In addition, the agreement provides for contingent payments from Merck to Bayer related to the successful achievement of sales-based milestones. In the first quarter of 2021, following the approval of Verquvo noted above, Merck determined it was probable that sales of Adempas and Verquvo in the future would trigger the remaining $400 million sales-based milestone payment that was outstanding under this agreement. Accordingly, Merck recorded a liability of $400 million and a corresponding increase to the intangible assets related to this collaboration. Merck also recognized $153 million of cumulative amortization expense related to the recognition of this milestone in the first six months of 2021. The intangible asset balance related to Adempas (which includes the acquired intangible asset balance, as well as capitalized sales-based milestone payments attributed to Adempas) was $920 million at June 30, 2021 and is being amortized over its estimated useful life through 2027 as supported by projected future cash flows, subject to impairment testing. The intangible asset balance related to Verquvo (which reflects the portion of the final sales-based milestone payment that was attributed to Verquvo) was $75 million at June 30, 2021 and is being amortized over its estimated useful life through 2031 as supported by projected future cash flows, subject to impairment testing. Summarized financial information related to this collaboration is as follows: Three Months Ended Six Months Ended ($ in millions) 2021 2020 2021 2020 Alliance revenue - Adempas/Verquvo $ 74 $ 79 $ 149 $ 133 Net sales of Adempas recorded by Merck 74 57 129 113 Net sales of Verquvo recorded by Merck 1 — 1 — Total sales $ 149 $ 136 $ 279 $ 246 Cost of sales (1) 39 28 229 57 Selling, general and administrative 32 17 58 28 Research and development 13 16 20 41 ($ in millions) June 30, 2021 December 31, 2020 Receivables from Bayer included in Other current assets $ 65 $ 65 Payables to Bayer included in Other Noncurrent Liabilities (2) 400 — (1) Includes amortization of intangible assets. Amount in the first six months of 2021 includes $153 million of cumulative amortization as noted above. (2) Represents accrued milestone payment.

Restructuring

Restructuring	6 Months Ended
	Jun. 30, 2021
Restructuring and Related Activities [Abstract]
Restructuring	Restructuring In 2019, Merck approved a new global restructuring program (Restructuring Program) as part of a worldwide initiative focused on further optimizing the Company’s manufacturing and supply network, as well as reducing its global real estate footprint. This program is a continuation of the Company’s plant rationalization, builds on prior restructuring programs and does not include any actions associated with the spin-off of Organon. As the Company continues to evaluate its global footprint and overall operating model, it subsequently identified additional actions under the Restructuring Program, and could identify further actions over time. The actions currently contemplated under the Restructuring Program are expected to be substantially completed by the end of 2023, with the cumulative pretax costs to be incurred by the Company to implement the program estimated to be approximately $3.0 billion. The Company estimates that approximately 70% of the cumulative pretax costs will result in cash outlays, primarily related to employee separation expense and facility shut-down costs. Approximately 30% of the cumulative pretax costs will be non-cash, relating primarily to the accelerated depreciation of facilities to be closed or divested. The Company recorded total pretax costs of $128 million and $149 million in the second quarter of 2021 and 2020, respectively, and $462 million and $315 million for the first six months of 2021 and 2020, respectively, related to restructuring program activities. Since inception of the Restructuring Program through June 30, 2021, Merck has recorded total pretax accumulated costs of approximately $2.3 billion. For the full year of 2021, the Company expects to record charges of approximately $700 million related to the Restructuring Program. For segment reporting, restructuring charges are unallocated expenses. The following tables summarize the charges related to restructuring program activities by type of cost: Three Months Ended June 30, 2021 Six Months Ended June 30, 2021 ($ in millions) Separation Accelerated Other Total Separation Accelerated Other Total Cost of sales $ — $ 11 $ 27 $ 38 $ — $ 21 $ 44 $ 65 Selling, general and administrative — 2 — 2 — 4 — 4 Research and development — 6 — 6 — 13 — 13 Restructuring costs 64 — 18 82 293 — 87 380 $ 64 $ 19 $ 45 $ 128 $ 293 $ 38 $ 131 $ 462 Three Months Ended June 30, 2020 Six Months Ended June 30, 2020 ($ in millions) Separation Accelerated Other Total Separation Accelerated Other Total Cost of sales $ — $ 31 $ (6) $ 25 $ — $ 56 $ 37 $ 93 Selling, general and administrative — 11 — 11 — 22 — 22 Research and development — 31 — 31 — 48 — 48 Restructuring costs 35 — 47 82 82 — 70 152 $ 35 $ 73 $ 41 $ 149 $ 82 $ 126 $ 107 $ 315 Separation costs are associated with actual headcount reductions, as well as those headcount reductions which were probable and could be reasonably estimated. Accelerated depreciation costs primarily relate to manufacturing, research and administrative facilities and equipment to be sold or closed as part of the programs. Accelerated depreciation costs represent the difference between the depreciation expense to be recognized over the revised useful life of the asset, based upon the anticipated date the site will be closed or divested or the equipment disposed of, and depreciation expense as determined utilizing the useful life prior to the restructuring actions. All the sites have and will continue to operate up through the respective closure dates and, since future undiscounted cash flows are sufficient to recover the respective book values, Merck is recording accelerated depreciation over the revised useful life of the site assets. Anticipated site closure dates, particularly related to manufacturing locations, have been and may continue to be adjusted to reflect changes resulting from regulatory or other factors. Other activity in 2021 and 2020 includes asset abandonment, facility shut-down and other related costs, as well as pretax gains and losses resulting from the sales of facilities and related assets. Additionally, other activity includes certain employee-related costs associated with pension and other postretirement benefit plans (see Note 11) and share-based compensation. The following table summarizes the charges and spending relating to restructuring program activities for the six months ended June 30, 2021: ($ in millions) Separation Accelerated Other Total Restructuring reserves January 1, 2021 $ 567 $ — $ 19 $ 586 Expense 293 38 131 462 (Payments) receipts, net (230) — (157) (387) Non-cash activity — (38) 48 10 Restructuring reserves June 30, 2021 (1) $ 630 $ — $ 41 $ 671

Financial Instruments

Financial Instruments	6 Months Ended
	Jun. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Financial Instruments	Financial Instruments Derivative Instruments and Hedging Activities The Company manages the impact of foreign exchange rate movements and interest rate movements on its earnings, cash flows and fair values of assets and liabilities through operational means and through the use of various financial instruments, including derivative instruments. A significant portion of the Company’s revenues and earnings in foreign affiliates is exposed to changes in foreign exchange rates. The objectives and accounting related to the Company’s foreign currency risk management program, as well as its interest rate risk management activities are discussed below. Foreign Currency Risk Management The Company has established revenue hedging, balance sheet risk management and net investment hedging programs to protect against volatility of future foreign currency cash flows and changes in fair value caused by changes in foreign exchange rates. The objective of the revenue hedging program is to reduce the variability caused by changes in foreign exchange rates that would affect the U.S. dollar value of future cash flows derived from foreign currency denominated sales, primarily the euro, Japanese yen and Chinese renminbi. To achieve this objective, the Company will hedge a portion of its forecasted foreign currency denominated third-party and intercompany distributor entity sales (forecasted sales) that are expected to occur over its planning cycle, typically no more than two years into the future. The Company will layer in hedges over time, increasing the portion of forecasted sales hedged as it gets closer to the expected date of the forecasted sales. The portion of forecasted sales hedged is based on assessments of cost-benefit profiles that consider natural offsetting exposures, revenue and exchange rate volatilities and correlations, and the cost of hedging instruments. The Company manages its anticipated transaction exposure principally with purchased local currency put options, forward contracts and purchased collar options. The fair values of these derivative contracts are recorded as either assets (gain positions) or liabilities (loss positions) in the Condensed Consolidated Balance Sheet. Changes in the fair value of derivative contracts are recorded each period in either current earnings or Other comprehensive income ( OCI ), depending on whether the derivative is designated as part of a hedge transaction and, if so, the type of hedge transaction. For derivatives that are designated as cash flow hedges, the unrealized gains or losses on these contracts are recorded in Accumulated other comprehensive income ( AOCI ) and reclassified into Sales when the hedged anticipated revenue is recognized. For those derivatives which are not designated as cash flow hedges, but serve as economic hedges of forecasted sales, unrealized gains or losses are recorded in Sales each period. The cash flows from both designated and non-designated contracts are reported as operating activities in the Condensed Consolidated Statement of Cash Flows. The Company does not enter into derivatives for trading or speculative purposes. The Company manages operating activities and net asset positions at each local subsidiary in order to mitigate the effects of exchange on monetary assets and liabilities. The Company also uses a balance sheet risk management program to mitigate the exposure of net monetary assets that are denominated in a currency other than a subsidiary’s functional currency from the effects of volatility in foreign exchange. In these instances, Merck principally utilizes forward exchange contracts to offset the effects of exchange on exposures denominated in developed country currencies, primarily the euro and Japanese yen. For exposures in developing country currencies, the Company will enter into forward contracts to partially offset the effects of exchange on exposures when it is deemed economical to do so based on a cost-benefit analysis that considers the magnitude of the exposure, the volatility of the exchange rate and the cost of the hedging instrument. The cash flows from these contracts are reported as operating activities in the Condensed Consolidated Statement of Cash Flows. Monetary assets and liabilities denominated in a currency other than the functional currency of a given subsidiary are remeasured at spot rates in effect on the balance sheet date with the effects of changes in spot rates reported in Other (income) expense, net . The forward contracts are not designated as hedges and are marked to market through Other (income) expense, net . Accordingly, fair value changes in the forward contracts help mitigate the changes in the value of the remeasured assets and liabilities attributable to changes in foreign currency exchange rates, except to the extent of the spot-forward differences. These differences are not significant due to the short-term nature of the contracts, which typically have average maturities at inception of less than one year. The Company also uses forward exchange contracts to hedge a portion of its net investment in foreign operations against movements in exchange rates. The forward contracts are designated as hedges of the net investment in a foreign operation. The unrealized gains or losses on these contracts are recorded in foreign currency translation adjustment within OCI and remain in AOCI until either the sale or complete or substantially complete liquidation of the subsidiary. The Company excludes certain portions of the change in fair value of its derivative instruments from the assessment of hedge effectiveness (excluded components). Changes in fair value of the excluded components are recognized in OCI . The Company recognizes in earnings the initial value of the excluded components on a straight-line basis over the life of the derivative instrument, rather than using the mark-to-market approach. The cash flows from these contracts are reported as investing activities in the Condensed Consolidated Statement of Cash Flows. Foreign exchange risk is also managed through the use of foreign currency debt. The Company’s senior unsecured euro-denominated notes have been designated as, and are effective as, economic hedges of the net investment in a foreign operation. Accordingly, foreign currency transaction gains or losses due to spot rate fluctuations on the euro-denominated debt instruments are included in foreign currency translation adjustment within OCI . The effects of the Company’s net investment hedges on OCI and the Consolidated Statement of Income are shown below: Amount of Pretax (Gain) Loss Recognized in Other Comprehensive Income (1) Amount of Pretax (Gain) Loss Recognized in Other (income) expense, net for Amounts Excluded from Effectiveness Testing Three Months Ended June 30, Six Months Ended June 30, Three Months Ended June 30, Six Months Ended June 30, ($ in millions) 2021 2020 2021 2020 2021 2020 2021 2020 Net Investment Hedging Relationships Foreign exchange contracts $ (3) $ 8 $ (28) $ 5 $ (4) $ (4) $ (8) $ (11) Euro-denominated notes 45 72 (122) 21 — — — — (1) No amounts were reclassified from AOCI into income related to the sale of a subsidiary. Interest Rate Risk Management The Company may use interest rate swap contracts on certain investing and borrowing transactions to manage its net exposure to interest rate changes and to reduce its overall cost of borrowing. The Company does not use leveraged swaps and, in general, does not leverage any of its investment activities that would put principal capital at risk. In January 2021, five interest rate swaps with a total notional amount of $1.15 billion matured. These swaps effectively converted the Company’s $1.15 billion, 3.875% fixed-rate notes due 2021 to variable rate debt. At June 30, 2021, the Company was a party to nine pay-floating, receive-fixed interest rate swap contracts designated as fair value hedges of fixed-rate notes in which the notional amounts match the amount of the hedged fixed-rate notes as detailed in the table below. June 30, 2021 ($ in millions) Par Value of Debt Number of Interest Rate Swaps Held Total Swap Notional Amount 2.40% notes due 2022 $ 1,000 4 $ 1,000 2.35% notes due 2022 1,250 5 1,250 The interest rate swap contracts are designated hedges of the fair value changes in the notes attributable to changes in the benchmark LIBOR swap rate. The fair value changes in the notes attributable to changes in the LIBOR swap rate are recorded in interest expense along with the offsetting fair value changes in the swap contracts. The cash flows from these contracts are reported as operating activities in the Condensed Consolidated Statement of Cash Flows. The table below presents the location of amounts recorded on the Condensed Consolidated Balance Sheet related to cumulative basis adjustments for fair value hedges: Carrying Amount of Hedged Liabilities Cumulative Amount of Fair Value Hedging Adjustment Increase (Decrease) Included in the Carrying Amount ($ in millions) June 30, 2021 December 31, 2020 June 30, 2021 December 31, 2020 Loans payable and current portion of long-term debt $ 1,261 $ 1,150 $ 11 $ — Long-Term Debt 1,022 2,301 23 53 Presented in the table below is the fair value of derivatives on a gross basis segregated between those derivatives that are designated as hedging instruments and those that are not designated as hedging instruments: June 30, 2021 December 31, 2020 Fair Value of Derivative U.S. Dollar Fair Value of Derivative U.S. Dollar ($ in millions) Asset Liability Asset Liability Derivatives Designated as Hedging Instruments Balance Sheet Caption Interest rate swap contracts Other current assets $ 12 $ — $ 1,250 $ 1 $ — $ 1,150 Interest rate swap contracts Other Assets 24 — 1,000 54 — 2,250 Foreign exchange contracts Other current assets 156 — 5,970 12 — 3,183 Foreign exchange contracts Other Assets 49 — 1,601 45 — 2,030 Foreign exchange contracts Accrued and other current liabilities — 40 2,850 — 217 5,049 Foreign exchange contracts Other Noncurrent Liabilities — 1 84 — 1 52 $ 241 $ 41 $ 12,755 $ 112 $ 218 $ 13,714 Derivatives Not Designated as Hedging Instruments Balance Sheet Caption Foreign exchange contracts Other current assets $ 92 $ — $ 6,981 $ 70 $ — $ 7,260 Foreign exchange contracts Accrued and other current liabilities — 133 9,690 — 307 11,810 $ 92 $ 133 $ 16,671 $ 70 $ 307 $ 19,070 $ 333 $ 174 $ 29,426 $ 182 $ 525 $ 32,784 As noted above, the Company records its derivatives on a gross basis in the Condensed Consolidated Balance Sheet. The Company has master netting agreements with several of its financial institution counterparties (see Concentrations of Credit Risk below). The following table provides information on the Company’s derivative positions subject to these master netting arrangements as if they were presented on a net basis, allowing for the right of offset by counterparty and cash collateral exchanged per the master agreements and related credit support annexes: June 30, 2021 December 31, 2020 ($ in millions) Asset Liability Asset Liability Gross amounts recognized in the condensed consolidated balance sheet $ 333 $ 174 $ 182 $ 525 Gross amounts subject to offset in master netting arrangements not offset in the condensed consolidated balance sheet (152) (152) (156) (156) Cash collateral received/posted (13) — — (36) Net amounts $ 168 $ 22 $ 26 $ 333 The table below provides information regarding the location and amount of pretax (gains) losses of derivatives designated in fair value or cash flow hedging relationships (including amounts attributable to discontinued operations): Sales Other (income) expense, net (1) Other comprehensive income (loss) Sales Other (income) expense, net (1) Other comprehensive income (loss) Three Months Ended June 30, Three Months Ended June 30, Three Months Ended June 30, Six Months Ended June 30, Six Months Ended June 30, Six Months Ended June 30, ($ in millions) 2021 2020 2021 2020 2021 2020 2021 2020 2021 2020 2021 2020 Financial Statement Line Items in which Effects of Fair Value or Cash Flow Hedges are Recorded $ 11,402 $ 9,353 $ (103) $ (387) $ 1,545 $ (2) $ 22,029 $ 19,641 $ (558) $ (325) $ 1,557 $ (200) (Gain) loss on fair value hedging relationships Interest rate swap contracts Hedged items — — (9) 1 — — — — (19) 68 — — Derivatives designated as hedging instruments — — (1) (8) — — — — — (76) — — Impact of cash flow hedging relationships Foreign exchange contracts Amount of gain recognized in OCI on derivatives — — — — (58) (109) — — — — 121 69 (Decrease) increase in Sales as a result of AOCI reclassifications (71) 42 — — 71 (42) (183) 88 — — 183 (88) Interest rate contracts Amount of gain recognized in Other (income) expense, net on derivatives — — — (1) — — — — (1) (2) — — Amount of loss recognized in OCI on derivatives — — — — — (1) — — — — (1) (2) (1) Interest expense is a component of Other (income) expense, net. The table below provides information regarding the income statement effects of derivatives not designated as hedging instruments (including amounts attributable to discontinued operations): Amount of Derivative Pretax (Gain) Loss Recognized in Income Three Months Ended Six Months Ended ($ in millions) 2021 2020 2021 2020 Derivatives Not Designated as Hedging Instruments Income Statement Caption Foreign exchange contracts (1) Other (income) expense, net $ 167 $ 49 $ 217 $ (131) Foreign exchange contracts (2) Sales 14 4 10 (3) Interest rate contracts (3) Other (income) expense, net — 9 — 9 (1) These derivative contracts primarily mitigate changes in the value of remeasured foreign currency denominated monetary assets and liabilities attributable to changes in foreign currency exchange rates. Amounts in 2021 include a loss on forward exchange contracts entered into in conjunction with the spin-off of Organon. (2) These derivative contracts serve as economic hedges of forecasted transactions. (3) These derivative contracts serve as economic hedges against rising treasury rates. At June 30, 2021, the Company estimates $52 million of pretax net unrealized losses on derivatives maturing within the next 12 months that hedge foreign currency denominated sales over that same period will be reclassified from AOCI to Sales . The amount ultimately reclassified to Sales may differ as foreign exchange rates change. Realized gains and losses are ultimately determined by actual exchange rates at maturity. Investments in Debt and Equity Securities Information on investments in debt and equity securities is as follows: June 30, 2021 December 31, 2020 Amortized Gross Unrealized Fair Amortized Gross Unrealized Fair ($ in millions) Gains Losses Gains Losses U.S. government and agency securities $ 82 $ — $ — $ 82 $ 84 $ — $ — $ 84 Corporate notes and bonds 4 — — 4 — — — — Foreign government bonds 2 — — 2 5 — — 5 Total debt securities $ 88 $ — $ — $ 88 $ 89 $ — $ — $ 89 Publicly traded equity securities (1) 1,579 1,787 Total debt and publicly traded equity securities $ 1,667 $ 1,876 (1) Unrealized net losses recorded in Other (income) expense, net on equity securities still held at June 30, 2021 were $18 million and $199 million in the second quarter and first six months of 2021, respectively. Unrealized net gains recorded in Other (income) expense, net on equity securities still held at June 30, 2020 were $464 million and $469 million in the second quarter and first six months of 2020, respectively. At June 30, 2021 and June 30, 2020, the Company also had $694 million and $487 million, respectively, of equity investments without readily determinable fair values included in Other Assets . The Company recognizes unrealized gains on these equity investments based on favorable observable price changes from transactions involving similar investments of the same investee and recognizes unrealized losses based on unfavorable observable price changes. During the first six months of 2021 , the Company recorded unrealized gains of $75 million and unrealized losses of $1 million in Other (income) expense, net related to these equity investments held at June 30, 2021. During the first six months of 2020 , the Company recorded unrealized gains of $18 million and unrealized losses of $3 million in Other (income) expense, net related to these equity investments held at June 30, 2020. Cumulative unrealized gains and cumulative unrealized losses based on observable prices changes for investments in equity investments without readily determinable fair values still held at June 30, 2021 were $244 million and $8 million, respectively. Fair Value Measurements Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The Company uses a fair value hierarchy which maximizes the use of observable inputs and minimizes the use of unobservable inputs when measuring fair value. There are three levels of inputs used to measure fair value with Level 1 having the highest priority and Level 3 having the lowest: Level 1 - Quoted prices (unadjusted) in active markets for identical assets or liabilities; Level 2 - Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities; Level 3 - Unobservable inputs that are supported by little or no market activity. Level 3 assets or liabilities are those whose values are determined using pricing models, discounted cash flow methodologies, or similar techniques with significant unobservable inputs, as well as assets or liabilities for which the determination of fair value requires significant judgment or estimation. If the inputs used to measure the financial assets and liabilities fall within more than one level described above, the categorization is based on the lowest level input that is significant to the fair value measurement of the instrument. Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis Financial assets and liabilities measured at fair value on a recurring basis are summarized below: Fair Value Measurements Using Fair Value Measurements Using Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total ($ in millions) June 30, 2021 December 31, 2020 Assets Investments Foreign government bonds $ — $ 2 $ — $ 2 $ — $ 5 $ — $ 5 Publicly traded equity securities 409 — — 409 780 — — 780 409 2 — 411 780 5 — 785 Other assets (1) U.S. government and agency securities 82 — — 82 84 — — 84 Corporate notes and bonds 4 — — 4 — — — — Publicly traded equity securities 1,170 — — 1,170 1,007 — — 1,007 1,256 — — 1,256 1,091 — — 1,091 Derivative assets (2) Forward exchange contracts — 203 — 203 — 90 — 90 Purchased currency options — 94 — 94 — 37 — 37 Interest rate swaps — 36 — 36 — 55 — 55 — 333 — 333 — 182 — 182 Total assets $ 1,665 $ 335 $ — $ 2,000 $ 1,871 $ 187 $ — $ 2,058 Liabilities Other liabilities Contingent consideration $ — $ — $ 879 $ 879 $ — $ — $ 841 $ 841 Derivative liabilities (2) Forward exchange contracts — 173 — 173 — 505 — 505 Written currency options — 1 — 1 — 20 — 20 — 174 — 174 — 525 — 525 Total liabilities $ — $ 174 $ 879 $ 1,053 $ — $ 525 $ 841 $ 1,366 (1) Investments included in other assets are restricted as to use, including for the payment of benefits under employee benefit plans. (2) The fair value determination of derivatives includes the impact of the credit risk of counterparties to the derivatives and the Company’s own credit risk, the effects of which were not significant. As of June 30, 2021 and December 31, 2020, Cash and cash equivalents included $7.5 billion and $6.8 billion of cash equivalents, respectively (which would be considered Level 2 in the fair value hierarchy). Contingent Consideration Summarized information about the changes in liabilities for contingent consideration associated with business acquisitions is as follows: Six Months Ended June 30, ($ in millions) 2021 2020 Fair value January 1 $ 841 $ 767 Additions — 97 Changes in estimated fair value (1) 50 40 Payments — (106) Other (12) — Fair value June 30 (2)(3) $ 879 $ 798 (1) Recorded in Cost of sales, Research and development expenses, and Other (income) expense, net . Includes cumulative translation adjustments. (2) Balance at June 30, 2021 includes $297 million recorded as a current liability for amounts expected to be paid within the next 12 months. (3) At June 30, 2021 and December 31, 2020, $759 million and $711 million, respectively, of the liabilities relate to the termination of the Sanofi Pasteur MSD joint venture in 2016. As part of the termination, Merck recorded a liability for contingent future royalty payments of 11.5% on net sales of all Merck products that were previously sold by the joint venture through December 31, 2024. The fair value of this liability is determined utilizing the estimated amount and timing of projected cash flows using a risk-adjusted discount rate of 8% to present value the cash flows. The additions to contingent consideration in 2020 relate to the acquisition of Themis (see Note 3). The payments of contingent consideration in 2020 relate to liabilities recorded in connection with the termination of the Sanofi-Pasteur MSD joint venture in 2016. Other Fair Value Measurements Some of the Company’s financial instruments, such as cash and cash equivalents, receivables and payables, are reflected in the balance sheet at carrying value, which approximates fair value due to their short-term nature. The estimated fair value of loans payable and long-term debt (including current portion) at June 30, 2021, was $29.5 billion compared with a carrying value of $26.5 billion and at December 31, 2020, was $36.0 billion compared with a carrying value of $31.8 billion. Fair value was estimated using recent observable market prices and would be considered Level 2 in the fair value hierarchy. Concentrations of Credit Risk On an ongoing basis, the Company monitors concentrations of credit risk associated with corporate and government issuers of securities and financial institutions with which it conducts business. Credit exposure limits are established to limit a concentration with any single issuer or institution. Cash and investments are placed in instruments that meet high credit quality standards as specified in the Company’s investment policy guidelines. The majority of the Company’s accounts receivable arise from product sales in the U.S., Europe and China and are primarily due from drug wholesalers and retailers, hospitals, government agencies, managed health care providers and pharmacy benefit managers. The Company monitors the financial performance and creditworthiness of its customers so that it can properly assess and respond to changes in their credit profile. The Company also continues to monitor global economic conditions, including the volatility associated with international sovereign economies, and associated impacts on the financial markets and its business. The Company has accounts receivable factoring agreements with financial institutions in certain countries to sell accounts receivable. The Company factored $2.4 billion and $2.1 billion of accounts receivable at June 30, 2021 and December 31, 2020, respectively, under these factoring arrangements, which reduced outstanding accounts receivable. The cash received from the financial institutions is reported within operating activities in the Consolidated Statement of Cash Flows. In certain of these factoring arrangements, for ease of administration, the Company will collect customer payments related to the factored receivables, which it then remits to the financial institutions. The net cash flows relating to these collections are reported as financing activities in the Consolidated Statement of Cash Flows. The cost of factoring such accounts receivable was de minimis . Derivative financial instruments are executed under International Swaps and Derivatives Association master agreements. The master agreements with several of the Company’s financial institution counterparties also include credit support annexes. These annexes contain provisions that require collateral to be exchanged depending on the value of the derivative assets and liabilities, the Company’s credit rating, and the credit rating of the counterparty. Cash collateral received by the Company from various counterparties was $13 million at June 30, 2021. The obligation to return such collateral is recorded in Accrued and other current liabilities . Cash collateral advanced by the Company to counterparties was $36 million at December 31, 2020.

Inventories

Inventories	6 Months Ended
	Jun. 30, 2021
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories consisted of: ($ in millions) June 30, 2021 December 31, 2020 Finished goods $ 1,778 $ 1,610 Raw materials and work in process 5,954 5,949 Supplies 175 146 Total (approximates current cost) 7,907 7,705 Decrease to LIFO cost 4 (81) $ 7,911 $ 7,624 Recognized as: Inventories $ 5,499 $ 5,554 Other assets 2,412 2,070 Amounts recognized as Other Assets are comprised almost entirely of raw materials and work in process inventories. At June 30, 2021 and December 31, 2020, these amounts included $1.7 billion and $1.8 billion, respectively, of inventories not expected to be sold within one year. In addition, these amounts included $681 million and $279 million at June 30, 2021 and December 31, 2020, respectively, of inventories produced in preparation for product launches.

Goodwill and Intangibles

Goodwill and Intangibles	6 Months Ended
	Jun. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangibles	Goodwill and IntangiblesIn connection with the spin-off of Organon (see Note 2), goodwill was reduced by $1.4 billion. Additionally, other intangibles, on a net basis, were reduced by $519 million, including products and products rights of $394 million and licenses of $125 million.

Contingencies

Contingencies	6 Months Ended
	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies The Company is involved in various claims and legal proceedings of a nature considered normal to its business, including product liability, intellectual property, and commercial litigation, as well as certain additional matters including governmental and environmental matters. In the opinion of the Company, it is unlikely that the resolution of these matters will be material to the Company’s financial condition, results of operations or cash flows. Given the nature of the litigation discussed below and the complexities involved in these matters, the Company is unable to reasonably estimate a possible loss or range of possible loss for such matters until the Company knows, among other factors, (i) what claims, if any, will survive dispositive motion practice, (ii) the extent of the claims, including the size of any potential class, particularly when damages are not specified or are indeterminate, (iii) how the discovery process will affect the litigation, (iv) the settlement posture of the other parties to the litigation and (v) any other factors that may have a material effect on the litigation. The Company records accruals for contingencies when it is probable that a liability has been incurred and the amount can be reasonably estimated. These accruals are adjusted periodically as assessments change or additional information becomes available. For product liability claims, a portion of the overall accrual is actuarially determined and considers such factors as past experience, number of claims reported and estimates of claims incurred but not yet reported. Individually significant contingent losses are accrued when probable and reasonably estimable. Legal defense costs expected to be incurred in connection with a loss contingency are accrued when probable and reasonably estimable. The Company’s decision to obtain insurance coverage is dependent on market conditions, including cost and availability, existing at the time such decisions are made. The Company has evaluated its risks and has determined that the cost of obtaining product liability insurance outweighs the likely benefits of the coverage that is available and, as such, has no insurance for most product liabilities. Product Liability Litigation Fosamax As previously disclosed, Merck is a defendant in product liability lawsuits in the U.S. involving Fosamax ( Fosamax Litigation). As of June 30, 2021, approximately 3,475 cases are pending against Merck in either a federal multidistrict litigation (Femur Fracture MDL) or state court. Plaintiffs in the vast majority of these cases generally allege that they sustained femur fractures and/or other bone injuries (Femur Fractures) in association with the use of Fosamax . In March 2014, the Femur Fracture MDL court dismissed with prejudice approximately 650 cases on preemption grounds. Plaintiffs in approximately 515 of those cases appealed that decision to the U.S. Court of Appeals for the Third Circuit (Third Circuit). In March 2017, the Third Circuit issued a decision reversing the Femur Fracture MDL court’s preemption ruling and remanding the appealed cases back to the Femur Fracture MDL court. In May 2019, the U.S. Supreme Court decided that the Third Circuit had incorrectly concluded that the issue of preemption should be resolved by a jury, and accordingly vacated the judgment of the Third Circuit and remanded the proceedings back to the Third Circuit to address the issue in a manner consistent with the Supreme Court’s opinion. In November 2019, the Third Circuit remanded the cases back to the District Court in order to allow that court to determine in the first instance whether the plaintiffs’ state law claims are preempted by federal law under the standards described by the Supreme Court in its opinion. Briefing on the issue is closed, and the parties await the decision of the District Court. Discovery is presently stayed in the Femur Fracture MDL and in the state court in California. As part of the spin-off of Organon, Organon is required to indemnify Merck for all liabilities relating to, arising from, or resulting from the Fosamax Litigation. Januvia/Janumet As previously disclosed, Merck is a defendant in product liability lawsuits in the U.S. involving Januvia and/or Janumet . As of June 30, 2021, Merck is aware of approximately 1,470 product users alleging that Januvia and/or Janumet caused the development of pancreatic cancer and other injuries. Most claims have been filed in multidistrict litigation before the U.S. District Court for the Southern District of California (MDL). On March 9, 2021, the MDL Court issued an omnibus order granting defendants’ summary judgment motions based on preemption and failure to establish general causation, as well as granting defendants’ motions to exclude plaintiffs’ expert witnesses. Outside of the MDL, the majority of claims have been filed in coordinated proceedings before the Superior Court of California, County of Los Angeles (California State Court). On April 6, 2021, the court in California issued an omnibus order granting defendants’ summary judgment motions and also granting defendants’ motions to exclude plaintiffs’ expert witnesses. As of June 30, 2021, six product users have claims pending against Merck in state courts other than California, including Illinois. In June 2017, the Illinois trial court denied Merck’s motion for summary judgment based on federal preemption. Merck appealed, and the Illinois appellate court affirmed in December 2018. Merck filed a petition for leave to appeal to the Illinois Supreme Court in February 2019. In April 2019, the Illinois Supreme Court stayed consideration of the pending petition to appeal until the U.S. Supreme Court issued its opinion in Merck Sharp & Dohme Corp. v. Albrecht (relating to the Fosamax matter discussed above). Merck filed the opinion in Albrecht with the Illinois Supreme Court in June 2019. The petition for leave to appeal was decided in September 2019, in which the Illinois Supreme Court directed the intermediate appellate court to reconsider its earlier ruling. The Illinois Appellate Court issued a favorable decision concluding, consistent with Albrecht , that preemption presents a legal question to be resolved by the court. In May 2020, the Illinois Appellate Court issued a mandate to the state trial court, which, as of March 31, 2021, had not scheduled a case management conference or otherwise taken action. In addition to the claims noted above, the Company has agreed to toll the statute of limitations for approximately 50 additional claims. The Company intends to continue defending against any remaining lawsuits. Governmental Proceedings As previously disclosed, the Company’s subsidiaries in China have received and may continue to receive inquiries regarding their operations from various Chinese governmental agencies. Some of these inquiries may be related to matters involving other multinational pharmaceutical companies, as well as Chinese entities doing business with such companies. The Company’s policy is to cooperate with these authorities and to provide responses as appropriate. As previously disclosed, from time to time, the Company receives inquiries and is the subject of preliminary investigation activities from competition and other governmental authorities in markets outside the U.S. These authorities may include regulators, administrative authorities, and law enforcement and other similar officials, and these preliminary investigation activities may include site visits, formal or informal requests or demands for documents or materials, inquiries or interviews and similar matters. Certain of these preliminary inquiries or activities may lead to the commencement of formal proceedings. Should those proceedings be determined adversely to the Company, monetary fines and/or remedial undertakings may be required. Commercial and Other Litigation Zetia Antitrust Litigation As previously disclosed, Merck, MSD, Schering Corporation, Schering-Plough Corporation, and MSP Singapore Company LLC (collectively, the Merck Defendants) are defendants in putative class action and opt-out lawsuits filed in 2018 on behalf of direct and indirect purchasers of Zetia alleging violations of federal and state antitrust laws, as well as other state statutory and common law causes of action. The cases have been consolidated for pretrial purposes in a federal multidistrict litigation before Judge Rebecca Beach Smith in the Eastern District of Virginia. In December 2018, the court denied the Merck Defendants’ motions to dismiss or stay the direct purchaser putative class actions pending bilateral arbitration. In August 2019, the district court adopted in full the report and recommendation of the magistrate judge with respect to the Merck Defendants’ motions to dismiss on non-arbitration issues, thereby granting in part and denying in part Merck Defendants’ motions to dismiss. In addition, in June 2019, the representatives of the putative direct purchaser class filed an amended complaint, and in August 2019, retailer opt-out plaintiffs filed an amended complaint. In December 2019, the district court granted the Merck Defendants’ motion to dismiss to the extent the motion sought dismissal of claims for overcharges paid by entities that purchased generic ezetimibe from Par Pharmaceutical, Inc. (Par Pharmaceutical) and dismissed any claims for such overcharges. In November 2019, the direct purchaser plaintiffs and the indirect purchaser plaintiffs filed motions for class certification. In August 2020, the district court granted in part the direct purchasers’ motion for class certification and certified a class of 35 direct purchasers and, in November 2020, the U.S. Court of Appeals for the Fourth Circuit granted the Merck Defendants’ motion for permission to appeal the district court’s order. In August 2021, the Fourth Circuit vacated the district court’s class certification order and remanded for further proceedings consistent with the court’s ruling. Also, in August 2020, the magistrate judge recommended that the court grant the motion for class certification filed by the putative indirect purchaser class. The Merck Defendants objected to this report and recommendation and are awaiting a decision from the district court. In August 2020, the Merck Defendants filed a motion for summary judgment and other motions, and plaintiffs filed a motion for partial summary judgment, and other motions. Those motions are now fully briefed, and the court has heard argument on certain of the motions. The court may hold additional hearings on the other motions. Trial in this matter has been adjourned. In September 2020, United Healthcare Services, Inc. filed a lawsuit in the U.S. District Court for the District of Minnesota against the Merck Defendants and others (the UHC Action). The UHC Action makes similar allegations as those made in the Zetia class action. In September 2020, the U.S. Judicial Panel on Multidistrict Litigation transferred the case to the Eastern District of Virginia to proceed with the multidistrict Zetia litigation already in progress. In December 2020, Humana Inc. filed a lawsuit in the Superior Court of the State of California, County of San Francisco, against Merck and others, alleging defendants violated state antitrust laws in multiple states. Also, in December 2020, Centene Corporation and others filed a lawsuit in the Superior Court of the State of California, County of San Francisco, against the same defendants as Humana. Both lawsuits allege similar anticompetitive acts to those alleged in the Zetia class action. In July 2021, the California Court ruled on defendants’ Motion to Quash for lack of personal jurisdiction, granting the motion as to the out-of-state claims against defendants, and ordering limited jurisdictional discovery with regard to the California claims. In June 2021, Kaiser Foundation Health Plan, Inc. similarly filed a lawsuit in the Superior Court of the State of California, County of San Francisco, against the same defendants as Humana and Centene. The Kaiser lawsuit alleges similar anticompetitive acts to those alleged in the Zetia class action. The Kaiser action was removed to the United States District Court for the Northern District of California on July 16, 2021. Also, on July 16, 2021, Humana filed another action against the Merck Defendants in New Jersey in the Bergen County Superior Court, re-asserting the claims that were dismissed in their California action. Patent Litigation From time to time, generic manufacturers of pharmaceutical products file abbreviated New Drug Applications (NDAs) with the FDA seeking to market generic forms of the Company’s products prior to the expiration of relevant patents owned by the Company. To protect its patent rights, the Company may file patent infringement lawsuits against such generic companies. Similar lawsuits defending the Company’s patent rights may exist in other countries. The Company intends to vigorously defend its patents, which it believes are valid, against infringement by companies attempting to market products prior to the expiration of such patents. As with any litigation, there can be no assurance of the outcomes, which, if adverse, could result in significantly shortened periods of exclusivity for these products and, with respect to products acquired through acquisitions, potentially significant intangible asset impairment charges. Bridion — Between January and November 2020, the Company received multiple Paragraph IV Certification Letters under the Hatch-Waxman Act notifying the Company that generic drug companies have filed applications to the FDA seeking pre-patent expiry approval to sell generic versions of Bridion (sugammadex) Injection. In March, April and December 2020, the Company filed patent infringement lawsuits in the U.S. District Courts for the District of New Jersey and the Northern District of West Virginia against those generic companies. All actions in the District of New Jersey have been consolidated. These lawsuits, which assert one or more patents covering sugammadex and methods of using sugammadex, automatically stay FDA approval of the generic applications until June 2023 or until adverse court decisions, if any, whichever may occur earlier. Mylan Pharmaceuticals Inc., Mylan API US LLC, and Mylan Inc. (Mylan) have filed motions to dismiss in the District of New Jersey for lack of venue and failure to state a claim against certain defendants, and in the Northern District of West Virginia for failure to state a claim against certain defendants. The New Jersey motion has not yet been decided, and the West Virginia action is stayed pending resolution of the New Jersey motion. The Company has settled with two generic companies providing that these generic companies can bring their generic versions of Bridion to the market in January 2026 or earlier under certain circumstances. Januvia, Janumet, Janumet XR — As previously disclosed, the FDA has granted pediatric exclusivity with respect to Januvia , Janumet , and J anumet XR , which provides a further six months of exclusivity in the U.S. beyond the expiration of all patents listed in the FDA’s Orange Book. Including this exclusivity, key patent protection extends to January 2023. The Company anticipates that sales of Januvia and Janumet in the U.S. will decline significantly after this loss of market exclusivity. However, Januvia , Janumet , and Janumet XR contain sitagliptin phosphate monohydrate and the Company has another patent covering certain phosphate salt and polymorphic forms of sitagliptin, which, if determined to be valid, would preclude generic manufacturers from making sitagliptin phosphate salt and polymorphic forms before that patent, inclusive of pediatric exclusivity, expires in 2027 (2027 salt/polymorph patent). In 2019, Par Pharmaceutical filed suit against the Company in the U.S. District Court for the District of New Jersey, seeking a declaratory judgment of invalidity of the 2027 salt/polymorph patent. In response, the Company filed a patent infringement lawsuit in the U.S. District Court for the District of Delaware against Par Pharmaceutical and additional companies that also indicated an intent to market generic versions of Januvia , Janumet , and Janumet XR following expiration of key patent protection, but prior to the expiration of the 2027 salt/ polymorph patent, and a later granted patent owned by the Company covering the Janumet formulation which, inclusive of pediatric exclusivity, expires in 2029. The Company also filed a patent infringement lawsuit against Mylan in the Northern District of West Virginia. The Judicial Panel of Multidistrict Litigation entered an order transferring the Company’s lawsuit against Mylan to the U.S. District Court for the District of Delaware for coordinated and consolidated pretrial proceedings with the other cases pending in that district. In February 2021, the Company amended its complaint against Apotex Inc. and Apotex Corp., additional defendants in the patent infringement lawsuits, to add infringement claims related to a patent that expires in 2025 and covers certain processes for manufacturing sitagliptin. The U.S. District Court for the District of Delaware has scheduled the lawsuits for a single three-day trial on invalidity issues in October 2021. The Court has scheduled separate one-day trials on infringement issues in November 2021 through January 2022, to the extent such trials are necessary. In the Company’s case against Mylan, the U.S. District Court for the Northern District of West Virginia has conditionally scheduled a three-day trial in December 2021 on all issues. The Company has settled with ten generic companies providing that these generic companies can bring their generic versions of Januvia and Janumet to the market in May 2027 or earlier under certain circumstances, and their generic versions of Janumet XR to the market in July 2026 or earlier under certain circumstances. Additionally, in 2019, Mylan filed a petition for Inter Partes Review (IPR) at the U.S. Patent and Trademark Office (USPTO) seeking invalidity of some, but not all, of the claims of the 2027 salt/polymorph patent, which other manufacturers joined. The USPTO instituted IPR proceedings in May 2020, finding a reasonable likelihood that the challenged claims are not valid. Three other generic companies filed similar IPRs, which were joined with Mylan in a single proceeding by the USPTO. A trial was held in February 2021 and a final decision was rendered in May 2021, holding that all of the challenged claims were valid. Mylan and two additional challengers have appealed the USPTO’s decision to the United States Court of Appeals for the Federal Circuit. In Germany, generic companies have sought the revocation of the Supplementary Protection Certificate (SPC) for Janumet . If the generic companies are successful, Janumet could lose market exclusivity in Germany with expiry of pediatric market exclusivity in September 2022. A hearing was held in June 2021 where the SPC for Janumet was nullified, which the Company has appealed. Challenges to the Janumet SPC have also occurred in other European countries, including Austria, Czech Republic, Finland, Hungary, Italy, Portugal, and Slovakia. Other Litigation There are various other pending legal proceedings involving the Company, principally product liability and intellectual property lawsuits. While it is not feasible to predict the outcome of such proceedings, in the opinion of the Company, either the likelihood of loss is remote or any reasonably possible loss associated with the resolution of such proceedings is not expected to be material to the Company’s financial condition, results of operations or cash flows either individually or in the aggregate. Legal Defense Reserves Legal defense costs expected to be incurred in connection with a loss contingency are accrued when probable and reasonably estimable. Some of the significant factors considered in the review of these legal defense reserves are as follows: the actual costs incurred by the Company; the development of the Company’s legal defense strategy and structure in light of the scope of its litigation; the number of cases being brought against the Company; the costs and outcomes of completed trials and the most current information regarding anticipated timing, progression, and related costs of pre-trial activities and trials in the associated litigation. The amount of legal defense reserves as of June 30, 2021 and December 31, 2020 of approximately $230 million and $235 million, respectively, represents the Company’s best estimate of the minimum amount of defense costs to be incurred in connection with its outstanding litigation; however, events such as additional trials and other events that could arise in the course of its litigation could affect the ultimate amount of legal defense costs to be incurred by the Company. The Company will continue to monitor its legal defense costs and review the adequacy of the associated reserves and may determine to increase the reserves at any time in the future if, based upon the factors set forth, it believes it would be appropriate to do so.

Equity

Equity	6 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Equity	Equity Three Months Ended June 30, Common Stock Other Retained Accumulated Treasury Stock Non- Total ($ and shares in millions except per share amounts) Shares Par Value Shares Cost Balance at April 1, 2020 3,577 $ 1,788 $ 39,697 $ 48,272 $ (6,391) 1,053 $ (57,161) $ 95 $ 26,300 Net income attributable to Merck & Co., Inc. — — — 3,002 — — — — 3,002 Other comprehensive loss, net of taxes — — — — (2) — — — (2) Cash dividends declared on common stock ($0.61 per share) — — — (1,550) — — — — (1,550) Share-based compensation plans and other — — (324) — — (5) 311 — (13) Net income attributable to noncontrolling interests — — — — — — — 8 8 Distributions attributable to noncontrolling interests — — — — — — — (1) (1) Balance at June 30, 2020 3,577 $ 1,788 $ 39,373 $ 49,724 $ (6,393) 1,048 $ (56,850) $ 102 $ 27,744 Balance at April 1, 2021 3,577 $ 1,788 $ 39,613 $ 48,888 $ (6,622) 1,046 $ (56,722) $ 94 $ 27,039 Net income attributable to Merck & Co., Inc. — — — 1,545 — — — — 1,545 Other comprehensive income, net of taxes — — — — 1,545 — — — 1,545 Cash dividends declared on common stock ($0.65 per share) — — — (1,656) — — — — (1,656) Treasury stock shares purchased — — — — — 3 (239) — (239) Spin-off of Organon & Co. — — 4,643 — 449 — — (1) 5,091 Share-based compensation plans and other — — (217) — — (5) 279 — 62 Net income attributable to noncontrolling interests — — — — — — — 1 1 Balance at June 30, 2021 3,577 $ 1,788 $ 44,039 $ 48,777 $ (4,628) 1,044 $ (56,682) $ 94 $ 33,388 Six Months Ended June 30, Common Stock Other Retained Accumulated Treasury Stock Non- Total ($ and shares in millions except per share amounts) Shares Par Value Shares Cost Balance at January 1, 2020 3,577 $ 1,788 $ 39,660 $ 46,602 $ (6,193) 1,038 $ (55,950) $ 94 $ 26,001 Net income attributable to Merck & Co., Inc. — — — 6,221 — — — — 6,221 Other comprehensive loss, net of taxes — — — — (200) — — — (200) Cash dividends declared on common stock ($1.22 per share) — — — (3,099) — — — — (3,099) Treasury stock shares purchased — — — — — 16 (1,281) — (1,281) Share-based compensation plans and other — — (287) — — (6) 381 — 94 Net income attributable to noncontrolling interests — — — — — — — 8 8 Balance at June 30, 2020 3,577 $ 1,788 $ 39,373 $ 49,724 $ (6,393) 1,048 $ (56,850) $ 102 $ 27,744 Balance at January 1, 2021 3,577 $ 1,788 $ 39,588 $ 47,362 $ (6,634) 1,047 $ (56,787) $ 87 $ 25,404 Net income attributable to Merck & Co., Inc. — — — 4,724 — — — — 4,724 Other comprehensive income, net of taxes — — — — 1,557 — — — 1,557 Cash dividends declared on common stock ($1.30 per share) — — — (3,309) — — — — (3,309) Treasury stock shares purchased — — — — — 3 (239) — (239) Spin-off of Organon & Co. — — 4,643 — 449 — — (1) 5,091 Share-based compensation plans and other — — (192) — — (6) 344 — 152 Net income attributable to noncontrolling interests — — — — — — — 8 8 Balance at June 30, 2021 3,577 $ 1,788 $ 44,039 $ 48,777 $ (4,628) 1,044 $ (56,682) $ 94 $ 33,388

Pension and Other Postretiremen

Pension and Other Postretirement Benefit Plans	6 Months Ended
	Jun. 30, 2021
Retirement Benefits [Abstract]
Pension and Other Postretirement Benefit Plans	Pension and Other Postretirement Benefit Plans The Company has defined benefit pension plans covering eligible employees in the U.S. and in certain of its international subsidiaries. The net periodic benefit cost of such plans (including certain costs reported as part of discontinued operations) consisted of the following components: Three Months Ended Six Months Ended 2021 2020 2021 2020 ($ in millions) U.S. International U.S. International U.S. International U.S. International Service cost $ 98 $ 87 $ 88 $ 73 $ 198 $ 179 $ 175 $ 146 Interest cost 106 30 109 33 202 59 217 68 Expected return on plan assets (191) (104) (195) (101) (379) (209) (388) (205) Amortization of unrecognized prior service credit (11) (4) (12) (3) (20) (9) (25) (6) Net loss amortization 58 38 76 31 142 78 152 62 Termination benefits 52 2 1 — 53 3 4 1 Curtailments 9 (27) — — 16 (27) 2 (1) Settlements — 2 9 2 — 2 9 2 $ 121 $ 24 $ 76 $ 35 $ 212 $ 76 $ 146 $ 67 The Company provides medical benefits, principally to its eligible U.S. retirees and similar benefits to their dependents, through its other postretirement benefit plans. The net credit of such plans consisted of the following components: Three Months Ended Six Months Ended ($ in millions) 2021 2020 2021 2020 Service cost $ 13 $ 13 $ 26 $ 26 Interest cost 11 14 22 29 Expected return on plan assets (20) (19) (39) (37) Amortization of unrecognized prior service credit (25) (22) (50) (45) Termination benefits 37 — 37 — Curtailments (27) — (28) (1) $ (11) $ (14) $ (32) $ (28) Net periodic benefit cost (credit) for pension and other postretirement benefit plans in the second quarter and first six months of 2021 includes expenses for curtailments, settlements and termination benefits provided to certain employees in connection with the spin-off of Organon. In connection with restructuring actions (see Note 5), termination charges were recorded on pension plans related to expanded eligibility for certain employees e x iting Merck. Also, in connection with these restructuring actions, curtailments and settlements were recorded on pension plans as noted in the table above. The components of net periodic benefit cost (credit) other than the service cost component are included in Other (income) expense, net (see Note 12), with the exception of certain amounts for termination benefits, curtailments and settlements, which are recorded in Restructuring costs if the event giving rise to the termination benefits, curtailment or settlement is related to restructuring actions or in Income from Discontinued Operations, Net of Taxes and Amounts Attributable to Noncontrolling Interests if related to the spin-off of Organon (each as noted above). The transfer of employees to Organon in connection with the spin-off triggered remeasurements of some of the Company’s pension plans. These remeasurements, which were calculated using discount rates and asset values as of the date of the spin-off, resulted in a $1.7 billion reduction to net pension liabilities primarily due to higher discount rates. In addition, $99 million of net pension liabilities were transferred to Organon. The remeasurements and plan transfers also resulted in a related adjustment to Accumulated Other Comprehensive Income

Other (Income) Expense, Net

Other (Income) Expense, Net	6 Months Ended
	Jun. 30, 2021
Other Income and Expenses [Abstract]
Other (Income) Expense, Net	Other (Income) Expense, Net Other (income) expense, net, consisted of: Three Months Ended Six Months Ended ($ in millions) 2021 2020 2021 2020 Interest income $ (9) $ (14) $ (20) $ (39) Interest expense 202 209 401 421 Exchange losses 114 24 155 78 Income from investments in equity securities, net (1) (280) (551) (854) (603) Net periodic defined benefit plan (credit) cost other than service cost (110) (80) (199) (170) Other, net (20) 25 (41) (12) $ (103) $ (387) $ (558) $ (325) (1) Includes net realized and unrealized gains and losses from investments in equity securities either owned directly or through ownership interests in investment funds. Unrealized gains and losses from investments that are directly owned are determined at the end of the reporting period, while ownership interests in investment funds are accounted for on a one quarter lag. The Company estimates that gains of approximately $380 million will be recorded in the third quarter of 2021 from ownership interests in investment funds. Interest paid for the six months ended June 30, 2021 and 2020 was $363 million and $387 million, respectively.

Taxes on Income

Taxes on Income	6 Months Ended
	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Taxes on Income	Taxes on Income The effective income tax rates from continuing operations of 29.3% and 14.4% for the second quarter of 2021 and 2020, respectively, and 15.8% and 15.6% for the first six months of 2021 and 2020, respectively. The effective income tax rates from continuing operations in the second quarter and first six months of 2021 reflect the unfavorable effect of a charge for the acquisition of Pandion for which no tax benefit was recognized. Additionally, the effective income tax rate from continuing operations for the first six months of 2021 reflects a net tax benefit of $207 million related to the settlement of certain federal income tax matters as discussed below. In the first quarter of 2021, the Internal Revenue Service (IRS) concluded its examinations of Merck’s 2015-2016 U.S. federal income tax returns. As a result, the Company was required to make a payment of $190 million (of which $172 million related to Merck continuing operations and $18 million related to Organon discontinued operations). The Company’s reserves for unrecognized tax benefits for the years under examination exceeded the adjustments relating to this examination period and therefore the Company recorded a $236 million net tax benefit in the first six months of 2021 (of which $207 million related to Merck continuing operations and $29 million related to Organon discontinued operations). This net benefit reflects reductions in reserves for unrecognized tax benefits and other related liabilities for tax positions relating to the years that were under examination.

Earnings Per Share

Earnings Per Share	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share The calculations of earnings per share are as follows: Three Months Ended Six Months Ended ($ and shares in millions except per share amounts) 2021 2020 2021 2020 Net Income from Continuing Operations Attributable to Merck & Co., Inc. $ 1,213 $ 2,341 $ 3,958 $ 4,812 Income from Discontinued Operations, Net of Taxes and Amounts Attributable to Noncontrolling Interests 332 661 766 1,409 Net Income Attributable to Merck & Co., Inc. $ 1,545 $ 3,002 $ 4,724 $ 6,221 Average common shares outstanding 2,533 2,527 2,532 2,531 Common shares issuable (1) 7 9 8 11 Average common shares outstanding assuming dilution 2,540 2,536 2,540 2,542 Basic Earnings per Common Share Attributable to Merck & Co., Inc. Common Shareholders: Income from Continuing Operations $ 0.48 $ 0.93 $ 1.56 $ 1.90 Income from Discontinued Operations 0.13 0.26 0.30 0.56 Net Income $ 0.61 $ 1.19 $ 1.87 $ 2.46 Earnings per Common Share Assuming Dilution Attributable to Merck & Co., Inc. Common Shareholders: Income from Continuing Operations $ 0.48 $ 0.92 $ 1.56 $ 1.89 Income from Discontinued Operations 0.13 0.26 0.30 0.55 Net Income $ 0.61 $ 1.18 $ 1.86 $ 2.45 (1) Issuable primarily under share-based compensation plans.

Other Comprehensive Income (Los

Other Comprehensive Income (Loss)	6 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Other Comprehensive Income (Loss)	Other Comprehensive Income (Loss) Changes in each component of other comprehensive income (loss) are as follows: Three Months Ended June 30, ($ in millions) Derivatives Investments Employee Foreign Currency Accumulated Other Balance April 1, 2020, net of taxes $ 135 $ — $ (4,201) $ (2,325) $ (6,391) Other comprehensive income (loss) before reclassification adjustments, pretax (110) — (21) 63 (68) Tax 23 — 6 16 45 Other comprehensive income (loss) before reclassification adjustments, net of taxes (87) — (15) 79 (23) Reclassification adjustments, pretax (42) (1) — 69 (3) — 27 Tax 9 — (15) — (6) Reclassification adjustments, net of taxes (33) — 54 — 21 Other comprehensive income (loss), net of taxes (120) — 39 79 (2) Balance June 30, 2020, net of taxes $ 15 $ — $ (4,162) $ (2,246) $ (6,393) Balance April 1, 2021, net of taxes $ (36) $ — $ (4,459) $ (2,127) $ (6,622) Other comprehensive income (loss) before reclassification adjustments, pretax (59) — 1,767 140 1,848 Tax 13 — (400) (8) (395) Other comprehensive income (loss) before reclassification adjustments, net of taxes (46) — 1,367 132 1,453 Reclassification adjustments, pretax 71 (1) — 55 (3) — 126 Tax (15) — (19) — (34) Reclassification adjustments, net of taxes 56 — 36 — 92 Other comprehensive income (loss), net of taxes 10 — 1,403 132 1,545 Spin-off of Organon (see Note 2) — — 28 421 449 Balance June 30, 2021, net of taxes $ (26) $ — $ (3,028) $ (1,574) $ (4,628) Six Months Ended June 30, ($ in millions) Derivatives Investments Employee Foreign Currency Accumulated Other Balance January 1, 2020, net of taxes $ 31 $ 18 $ (4,261) $ (1,981) $ (6,193) Other comprehensive income (loss) before reclassification adjustments, pretax 68 3 (21) (270) (220) Tax (14) — 11 5 2 Other comprehensive income (loss) before reclassification adjustments, net of taxes 54 3 (10) (265) (218) Reclassification adjustments, pretax (89) (1) (21) (2) 138 (3) — 28 Tax 19 — (29) — (10) Reclassification adjustments, net of taxes (70) (21) 109 — 18 Other comprehensive income (loss), net of taxes (16) (18) 99 (265) (200) Balance June 30, 2020, net of taxes $ 15 $ — $ (4,162) $ (2,246) $ (6,393) Balance January 1, 2021, net of taxes $ (266) $ — $ (4,540) $ (1,828) $ (6,634) Other comprehensive income (loss) before reclassification adjustments, pretax 121 — 1,763 (71) 1,813 Tax (25) — (401) (96) (522) Other comprehensive income (loss) before reclassification adjustments, net of taxes 96 — 1,362 (167) 1,291 Reclassification adjustments, pretax 182 (1) — 142 (3) — 324 Tax (38) — (20) — (58) Reclassification adjustments, net of taxes 144 — 122 — 266 Other comprehensive income (loss), net of taxes 240 — 1,484 (167) 1,557 Spin-off of Organon (see Note 2) — — 28 421 449 Balance June 30, 2021, net of taxes $ (26) $ — $ (3,028) $ (1,574) $ (4,628) (1) Primarily relates to foreign currency cash flow hedges that were reclassified from AOCI to Sales . (2) Represents net realized (gains) losses on the sales of available-for-sale debt securities that were reclassified from AOCI to Other (income) expense, net . (3) Includes net amortization of prior service cost and actuarial gains and losses included in net periodic benefit cost (see Note 11).

Segment Reporting

Segment Reporting	6 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting The Company’s operations are principally managed on a products basis and include two operating segments, which are the Pharmaceutical and Animal Health segments, both of which are reportable segments. The Pharmaceutical segment includes human health pharmaceutical and vaccine products. Human health pharmaceutical products consist of therapeutic and preventive agents, generally sold by prescription, for the treatment of human disorders. The Company sells these human health pharmaceutical products primarily to drug wholesalers and retailers, hospitals, government agencies and managed health care providers such as health maintenance organizations, pharmacy benefit managers and other institutions. Human health vaccine products consist of preventive pediatric, adolescent and adult vaccines, primarily administered at physician offices. The Company sells these human health vaccines primarily to physicians, wholesalers, physician distributors and government entities. A large component of pediatric and adolescent vaccine sales are made to the U.S. Centers for Disease Control and Prevention Vaccines for Children program, which is funded by the U.S. government. Additionally, the Company sells vaccines to the Federal government for placement into vaccine stockpiles. The Animal Health segment discovers, develops, manufactures and markets a wide range of veterinary pharmaceutical and vaccine products, as well as health management solutions and services, for the prevention, treatment and control of disease in all major livestock and companion animal species. The Company also offers an extensive suite of digitally connected identification, traceability and monitoring products. The Company sells its products to veterinarians, distributors and animal producers. The Company previously had a Healthcare Services segment that provided services and solutions focused on engagement, health analytics and clinical services to improve the value of care delivered to patients. The Company divested the remaining businesses in this segment during the first quarter of 2020. Sales of the Company’s products were as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 ($ in millions) U.S. Int’l Total U.S. Int’l Total U.S. Int’l Total U.S. Int’l Total Pharmaceutical: Oncology Keytruda $ 2,347 $ 1,829 $ 4,176 $ 2,043 $ 1,345 $ 3,388 $ 4,528 $ 3,548 $ 8,076 $ 3,949 $ 2,722 $ 6,672 Alliance revenue - Lynparza (1) 124 124 248 105 73 178 242 233 475 190 133 323 Alliance revenue - Lenvima (1) 88 93 181 98 53 151 173 137 310 188 91 279 Vaccines Gardasil/Gardasil 9 454 781 1,234 168 488 656 766 1,385 2,151 629 1,124 1,753 ProQuad/M-M-R II /Varivax 386 130 516 263 115 378 718 246 965 596 217 813 RotaTeq 111 97 208 100 68 168 229 137 366 241 150 391 Pneumovax 23 100 52 152 21 96 117 173 150 323 203 170 373 Vaqta 22 34 56 17 11 28 47 43 90 47 41 88 Hospital Acute Care Bridion 197 190 387 107 117 224 364 363 727 250 274 524 Prevymis 37 56 93 28 35 63 72 103 174 55 68 123 Noxafil 14 52 66 6 67 73 29 104 133 14 154 168 Primaxin — 60 60 1 63 64 — 125 125 1 114 115 Cancidas 1 53 54 (2) 45 43 3 108 111 1 98 98 Invanz (4) 52 48 — 43 43 — 104 104 6 102 108 Zerbaxa (2) 1 (1) 17 15 32 (4) (5) (9) 37 32 69 Immunology Simponi — 202 202 — 191 191 — 416 416 — 406 406 Remicade — 75 75 — 73 73 — 160 160 — 160 160 Neuroscience Belsomra 14 63 78 22 61 84 32 125 157 49 114 163 Virology Isentress/Isentress HD 74 118 192 76 120 196 145 256 401 151 290 441 Cardiovascular Alliance revenue-Adempas/Verquvo (2) 81 (7) 74 73 6 79 149 — 149 122 11 133 Adempas — 74 74 — 57 57 — 129 129 — 113 113 Diabetes Januvia 284 500 784 413 441 854 632 961 1,593 768 860 1,628 Janumet 74 403 477 143 348 490 158 805 962 256 737 993 Other pharmaceutical (3) 245 301 546 259 289 548 485 644 1,130 513 637 1,149 Total Pharmaceutical segment sales 4,647 5,333 9,980 3,958 4,220 8,178 8,941 10,277 19,218 8,266 8,818 17,083 Animal Health: Livestock 161 659 821 122 526 648 318 1,322 1,640 284 1,102 1,386 Companion Animals 298 353 651 220 233 453 578 672 1,250 442 486 928 Total Animal Health segment sales 459 1,012 1,472 342 759 1,101 896 1,994 2,890 726 1,588 2,314 Other segment sales (4) — — — — — — — — — 23 — 23 Total segment sales 5,106 6,345 11,452 4,300 4,979 9,279 9,837 12,271 22,108 9,015 10,406 19,420 Other (5) (6) (44) (50) 22 52 74 53 (132) (79) 38 182 221 $ 5,100 $ 6,301 $ 11,402 $ 4,322 $ 5,031 $ 9,353 $ 9,890 $ 12,139 $ 22,029 $ 9,053 $ 10,588 $ 19,641 U.S. plus international may not equal total due to rounding. (1) Alliance revenue represents Merck’s share of profits, which are product sales net of cost of sales and commercialization costs (see Note 4). (2) Alliance revenue represents Merck’s share of profits from sales in Bayer’s marketing territories, which are product sales net of cost of sales and commercialization costs (see Note 4). (3) Other pharmaceutical primarily reflects sales of other human health pharmaceutical products, including products within the franchises not listed separately. (4) Represents sales for the Healthcare Services segment. All the businesses in the Healthcare Services segment were fully divested in the first quarter of 2020. (5) Other is primarily comprised of miscellaneous corporate revenues, including revenue hedging activities, as well as third-party manufacturing sales. Product sales are recorded net of the provision for discounts, including chargebacks, which are customer discounts that occur when a contracted customer purchases through an intermediary wholesale purchaser, and rebates that are owed based upon definitive contractual agreements or legal requirements with private sector and public sector (Medicaid and Medicare Part D) benefit providers, after the final dispensing of the product by a pharmacy to a benefit plan participant. These discounts, in the aggregate, reduced U.S. sales by $3.1 billion and $2.6 billion for the three months ended June 30, 2021 and 2020, respectively, and $6.0 billion and $5.4 billion for the six months ended June 30, 2021 and 2020, respectively. Consolidated sales by geographic area where derived are as follows: Three Months Ended Six Months Ended ($ in millions) 2021 2020 2021 2020 United States $ 5,100 $ 4,322 $ 9,890 $ 9,053 Europe, Middle East and Africa 3,333 2,622 6,569 5,591 China 975 623 1,697 1,269 Japan 661 621 1,291 1,204 Asia Pacific (other than China and Japan) 594 489 1,168 1,015 Latin America 532 423 1,032 875 Other 207 253 382 634 $ 11,402 $ 9,353 $ 22,029 $ 19,641 A reconciliation of segment profits to Income from Continuing Operations Before Taxes is as follows: Three Months Ended Six Months Ended ($ in millions) 2021 2020 2021 2020 Segment profits: Pharmaceutical segment $ 7,257 $ 5,832 $ 13,845 $ 12,209 Animal Health segment 552 408 1,124 887 Other segment — — — 2 Total segment profits 7,809 6,240 14,969 13,098 Other profits (79) 43 (113) 163 Unallocated: Interest income 9 14 20 39 Interest expense (202) (209) (401) (421) Amortization (357) (599) (871) (988) Depreciation (332) (367) (673) (733) Research and development (4,175) (1,956) (6,480) (4,020) Restructuring costs (82) (82) (380) (152) Other unallocated, net (874) (343) (1,367) (1,284) $ 1,717 $ 2,741 $ 4,704 $ 5,702 Pharmaceutical segment profits are comprised of segment sales less standard costs, as well as selling, general and administrative expenses directly incurred by the segment. Animal Health segment profits are comprised of segment sales, less all cost of sales, as well as selling, general and administrative expenses and research and development costs directly incurred by the segment. For internal management reporting presented to the chief operating decision maker, Merck does not allocate the remaining cost of sales not included in segment profits as described above, research and development expenses incurred in Merck Research Laboratories, the Company’s research and development division that focuses on human health-related activities, or general and administrative expenses, nor the cost of financing these activities. Separate divisions maintain responsibility for monitoring and managing these costs, including depreciation related to fixed assets utilized by these divisions and, therefore, they are not included in segment profits. In addition, costs related to restructuring activities, as well as the amortization of intangible assets and purchase accounting adjustments are not allocated to segments. Other profits are primarily comprised of miscellaneous corporate profits, as well as operating profits related to third-party manufacturing sales. Other unallocated, net, includes expenses from corporate and manufacturing cost centers, goodwill and other intangible asset impairment charges, gains or losses on sales of businesses, expense or income related to changes in the estimated fair value measurement of liabilities for contingent consideration, and other miscellaneous income or expense items.

Basis of Presentation (Policies

Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of PresentationThe accompanying unaudited condensed consolidated financial statements of Merck & Co., Inc. (Merck or the Company) have been prepared pursuant to the rules and regulations for reporting on Form 10-Q. Accordingly, certain information and disclosures required by accounting principles generally accepted in the United States (U.S.) (GAAP) for complete consolidated financial statements are not included herein. These interim statements should be read in conjunction with the audited financial statements and notes thereto included in Merck’s Form 10-K filed on February 25, 2021.The results of operations of any interim period are not necessarily indicative of the results of operations for the full year. In the Company’s opinion, all adjustments necessary for a fair statement of these interim statements have been included and are of a normal and recurring nature.
Recently Adopted and Issued Accounting Standards	Recently Adopted Accounting Standards In December 2019, the Financial Accounting Standards Board (FASB) issued amended guidance on the accounting and reporting of income taxes. The guidance is intended to simplify the accounting for income taxes by removing exceptions related to certain intraperiod tax allocations and deferred tax liabilities, clarifying guidance primarily related to evaluating the step-up tax basis for goodwill in a business combination, and reflecting enacted changes in tax laws or rates in the annual effective tax rate. The Company adopted the new guidance effective January 1, 2021. There was no impact to the Company’s consolidated financial statements upon adoption. In January 2020, the FASB issued new guidance intended to clarify certain interactions between accounting standards related to equity securities, equity method investments and certain derivatives. The guidance addresses accounting for the transition into and out of the equity method of accounting and measuring certain purchased options and forward contracts to acquire investments. The Company adopted the new guidance effective January 1, 2021. There was no impact to the Company’s consolidated financial statements upon adoption. Recently Issued Accounting Standard Not Yet Adopted In March 2020, the FASB issued optional guidance to ease the potential burden in accounting for (or recognizing the effects of) reference rate reform on financial reporting and subsequently issued clarifying amendments. The guidance provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships, and other transactions that reference the London Interbank Offered Rate (LIBOR) or another reference rate expected to be discontinued because of reference rate reform. The optional guidance is effective upon issuance and can be applied on a prospective basis at any time between January 1, 2020 through December 31, 2022. The Company is currently evaluating the impact of adoption on its consolidated financial statements.
Legal Costs, Policy	Legal defense costs expected to be incurred in connection with a loss contingency are accrued when probable and reasonably estimable.

Spin-Off of Organon & Co. (Tabl

Spin-Off of Organon & Co. (Tables)	6 Months Ended
	Jun. 30, 2021
Discontinued Operations and Disposal Groups [Abstract]
Disposal Groups, Including Discontinued Operations	Details of Income from discontinued operations, net of taxes and amounts attributable to noncontrolling interests are as follows: Three Months Ended Six Months Ended ($ in millions) 2021 (1) 2020 2021 (1) 2020 Sales $ 1,059 $ 1,519 $ 2,512 $ 3,288 Costs, Expenses and Other Cost of sales 318 412 789 895 Selling, general and administrative 431 293 877 657 Research and development 50 38 103 72 Restructuring costs — 1 1 3 Other (income) expense, net (23) (4) (15) 4 776 740 1,755 1,631 Income from discontinued operations before taxes 283 779 757 1,657 Tax (benefit) provision (49) 114 (12) 239 Income from discontinued operations, net of taxes 332 665 769 1,418 Less: Income of discontinued operations attributable to noncontrolling interests — 4 3 9 Income from discontinued operations, net of taxes and amounts attributable to noncontrolling interests $ 332 $ 661 $ 766 $ 1,409 (1) Reflects amounts through the June 2, 2021 spin-off date. Details of assets and liabilities of discontinued operations are as follows: ($ in millions) December 31, 2020 Cash and cash equivalents $ 12 Accounts receivable, less allowance for doubtful accounts 1,048 Inventories 756 Other current assets 867 Current assets of discontinued operations $ 2,683 Property, plant and equipment, net $ 986 Goodwill 1,356 Other intangibles, net 503 Other assets 330 Noncurrent Assets of Discontinued Operations $ 3,175 Trade accounts payable $ 267 Accrued and other current liabilities 841 Income taxes payable (22) Total current liabilities of discontinued operations $ 1,086 Deferred income taxes $ 10 Other noncurrent liabilities 176 Noncurrent Liabilities of Discontinued Operations $ 186

Acquisitions, Research Collab_2

Acquisitions, Research Collaborations and License Agreements (Tables)	6 Months Ended
	Jun. 30, 2021
Business Combinations [Abstract]
Fair Value of Assets Acquired and Liabilities Assumed	The estimated fair value of assets acquired and liabilities assumed from ArQule is as follows: ($ in millions) January 16, 2020 Cash and cash equivalents $ 145 IPR&D MK-1026 (formerly ARQ 531) (1) 2,280 Licensing arrangement for ARQ 087 80 Deferred income tax liabilities (361) Other assets and liabilities, net 34 Total identifiable net assets 2,178 Goodwill (2) 512 Consideration transferred $ 2,690 (1) The estimated fair value of the identifiable intangible asset related to IPR&D was determined using an income approach. The future net cash flows were discounted to present value utilizing a discount rate of 12.5%. Actual cash flows are likely to be different than those assumed. (2) The goodwill was allocated to the Pharmaceutical segment and is not deductible for tax purposes.

Collaborative Arrangements (Tab

Collaborative Arrangements (Tables)	6 Months Ended
	Jun. 30, 2021
Collaborative Arrangements [Abstract]
Collaboration Arrangements	Summarized financial information related to this collaboration is as follows: Three Months Ended Six Months Ended ($ in millions) 2021 2020 2021 2020 Alliance revenue - Lynparza $ 248 $ 178 $ 475 $ 323 Alliance revenue - Koselugo 8 — 14 — Total alliance revenue $ 256 $ 178 $ 489 $ 323 Cost of sales (1) 42 137 84 164 Selling, general and administrative 43 39 83 72 Research and development 31 37 60 73 ($ in millions) June 30, 2021 December 31, 2020 Receivables from AstraZeneca included in Other current assets $ 258 $ 215 Payables to AstraZeneca included in Accrued and other current liabilities (2) 418 423 (1) Represents amortization of capitalized milestone payments. (2) Includes accrued milestone payments. Summarized financial information related to this collaboration is as follows: Three Months Ended Six Months Ended ($ in millions) 2021 2020 2021 2020 Alliance revenue - Lenvima $ 181 $ 151 $ 310 $ 279 Cost of sales (1) 47 135 94 170 Selling, general and administrative 31 19 54 31 Research and development 57 56 121 120 ($ in millions) June 30, 2021 December 31, 2020 Receivables from Eisai included in Other current assets $ 212 $ 157 Payables to Eisai included in Accrued and other current liabilities (2) 600 335 Payables to Eisai included in Other Noncurrent Liabilities (3) — 600 (1) Represents amortization of capitalized milestone payments. (2) Includes accrued milestone and future option payments. (3) Includes accrued milestone payments. Summarized financial information related to this collaboration is as follows: Three Months Ended Six Months Ended ($ in millions) 2021 2020 2021 2020 Alliance revenue - Adempas/Verquvo $ 74 $ 79 $ 149 $ 133 Net sales of Adempas recorded by Merck 74 57 129 113 Net sales of Verquvo recorded by Merck 1 — 1 — Total sales $ 149 $ 136 $ 279 $ 246 Cost of sales (1) 39 28 229 57 Selling, general and administrative 32 17 58 28 Research and development 13 16 20 41 ($ in millions) June 30, 2021 December 31, 2020 Receivables from Bayer included in Other current assets $ 65 $ 65 Payables to Bayer included in Other Noncurrent Liabilities (2) 400 — (1) Includes amortization of intangible assets. Amount in the first six months of 2021 includes $153 million of cumulative amortization as noted above. (2) Represents accrued milestone payment.

Restructuring (Tables)

Restructuring (Tables)	6 Months Ended
	Jun. 30, 2021
Restructuring and Related Activities [Abstract]
Charges Related to Restructuring Program Activities by Type of Cost	The following tables summarize the charges related to restructuring program activities by type of cost: Three Months Ended June 30, 2021 Six Months Ended June 30, 2021 ($ in millions) Separation Accelerated Other Total Separation Accelerated Other Total Cost of sales $ — $ 11 $ 27 $ 38 $ — $ 21 $ 44 $ 65 Selling, general and administrative — 2 — 2 — 4 — 4 Research and development — 6 — 6 — 13 — 13 Restructuring costs 64 — 18 82 293 — 87 380 $ 64 $ 19 $ 45 $ 128 $ 293 $ 38 $ 131 $ 462 Three Months Ended June 30, 2020 Six Months Ended June 30, 2020 ($ in millions) Separation Accelerated Other Total Separation Accelerated Other Total Cost of sales $ — $ 31 $ (6) $ 25 $ — $ 56 $ 37 $ 93 Selling, general and administrative — 11 — 11 — 22 — 22 Research and development — 31 — 31 — 48 — 48 Restructuring costs 35 — 47 82 82 — 70 152 $ 35 $ 73 $ 41 $ 149 $ 82 $ 126 $ 107 $ 315
Charges and Spending Relating to Restructuring Activities by Program	The following table summarizes the charges and spending relating to restructuring program activities for the six months ended June 30, 2021: ($ in millions) Separation Accelerated Other Total Restructuring reserves January 1, 2021 $ 567 $ — $ 19 $ 586 Expense 293 38 131 462 (Payments) receipts, net (230) — (157) (387) Non-cash activity — (38) 48 10 Restructuring reserves June 30, 2021 (1) $ 630 $ — $ 41 $ 671

Financial Instruments (Tables)

Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Effect of Net Investment Hedges on OCI and the Consolidated Statement of Income	The effects of the Company’s net investment hedges on OCI and the Consolidated Statement of Income are shown below: Amount of Pretax (Gain) Loss Recognized in Other Comprehensive Income (1) Amount of Pretax (Gain) Loss Recognized in Other (income) expense, net for Amounts Excluded from Effectiveness Testing Three Months Ended June 30, Six Months Ended June 30, Three Months Ended June 30, Six Months Ended June 30, ($ in millions) 2021 2020 2021 2020 2021 2020 2021 2020 Net Investment Hedging Relationships Foreign exchange contracts $ (3) $ 8 $ (28) $ 5 $ (4) $ (4) $ (8) $ (11) Euro-denominated notes 45 72 (122) 21 — — — — (1) No amounts were reclassified from AOCI into income related to the sale of a subsidiary.
Summary of Interest Rate Swaps Held	At June 30, 2021, the Company was a party to nine pay-floating, receive-fixed interest rate swap contracts designated as fair value hedges of fixed-rate notes in which the notional amounts match the amount of the hedged fixed-rate notes as detailed in the table below. June 30, 2021 ($ in millions) Par Value of Debt Number of Interest Rate Swaps Held Total Swap Notional Amount 2.40% notes due 2022 $ 1,000 4 $ 1,000 2.35% notes due 2022 1,250 5 1,250
Amounts Recorded on Balance Sheet Related to Fair Value Hedges	The table below presents the location of amounts recorded on the Condensed Consolidated Balance Sheet related to cumulative basis adjustments for fair value hedges: Carrying Amount of Hedged Liabilities Cumulative Amount of Fair Value Hedging Adjustment Increase (Decrease) Included in the Carrying Amount ($ in millions) June 30, 2021 December 31, 2020 June 30, 2021 December 31, 2020 Loans payable and current portion of long-term debt $ 1,261 $ 1,150 $ 11 $ — Long-Term Debt 1,022 2,301 23 53
Fair Value of Derivatives on a Gross Basis Segregated between those Derivatives that are Designated as Hedging Instruments and those that are Not Designated as Hedging Instruments	Presented in the table below is the fair value of derivatives on a gross basis segregated between those derivatives that are designated as hedging instruments and those that are not designated as hedging instruments: June 30, 2021 December 31, 2020 Fair Value of Derivative U.S. Dollar Fair Value of Derivative U.S. Dollar ($ in millions) Asset Liability Asset Liability Derivatives Designated as Hedging Instruments Balance Sheet Caption Interest rate swap contracts Other current assets $ 12 $ — $ 1,250 $ 1 $ — $ 1,150 Interest rate swap contracts Other Assets 24 — 1,000 54 — 2,250 Foreign exchange contracts Other current assets 156 — 5,970 12 — 3,183 Foreign exchange contracts Other Assets 49 — 1,601 45 — 2,030 Foreign exchange contracts Accrued and other current liabilities — 40 2,850 — 217 5,049 Foreign exchange contracts Other Noncurrent Liabilities — 1 84 — 1 52 $ 241 $ 41 $ 12,755 $ 112 $ 218 $ 13,714 Derivatives Not Designated as Hedging Instruments Balance Sheet Caption Foreign exchange contracts Other current assets $ 92 $ — $ 6,981 $ 70 $ — $ 7,260 Foreign exchange contracts Accrued and other current liabilities — 133 9,690 — 307 11,810 $ 92 $ 133 $ 16,671 $ 70 $ 307 $ 19,070 $ 333 $ 174 $ 29,426 $ 182 $ 525 $ 32,784
Information on Derivative Positions Subject to Master Netting Arrangements as if they were Presented on a Net Basis	The following table provides information on the Company’s derivative positions subject to these master netting arrangements as if they were presented on a net basis, allowing for the right of offset by counterparty and cash collateral exchanged per the master agreements and related credit support annexes: June 30, 2021 December 31, 2020 ($ in millions) Asset Liability Asset Liability Gross amounts recognized in the condensed consolidated balance sheet $ 333 $ 174 $ 182 $ 525 Gross amounts subject to offset in master netting arrangements not offset in the condensed consolidated balance sheet (152) (152) (156) (156) Cash collateral received/posted (13) — — (36) Net amounts $ 168 $ 22 $ 26 $ 333
Location and Amount of Pretax (Gains) Losses of Derivatives	The table below provides information regarding the location and amount of pretax (gains) losses of derivatives designated in fair value or cash flow hedging relationships (including amounts attributable to discontinued operations): Sales Other (income) expense, net (1) Other comprehensive income (loss) Sales Other (income) expense, net (1) Other comprehensive income (loss) Three Months Ended June 30, Three Months Ended June 30, Three Months Ended June 30, Six Months Ended June 30, Six Months Ended June 30, Six Months Ended June 30, ($ in millions) 2021 2020 2021 2020 2021 2020 2021 2020 2021 2020 2021 2020 Financial Statement Line Items in which Effects of Fair Value or Cash Flow Hedges are Recorded $ 11,402 $ 9,353 $ (103) $ (387) $ 1,545 $ (2) $ 22,029 $ 19,641 $ (558) $ (325) $ 1,557 $ (200) (Gain) loss on fair value hedging relationships Interest rate swap contracts Hedged items — — (9) 1 — — — — (19) 68 — — Derivatives designated as hedging instruments — — (1) (8) — — — — — (76) — — Impact of cash flow hedging relationships Foreign exchange contracts Amount of gain recognized in OCI on derivatives — — — — (58) (109) — — — — 121 69 (Decrease) increase in Sales as a result of AOCI reclassifications (71) 42 — — 71 (42) (183) 88 — — 183 (88) Interest rate contracts Amount of gain recognized in Other (income) expense, net on derivatives — — — (1) — — — — (1) (2) — — Amount of loss recognized in OCI on derivatives — — — — — (1) — — — — (1) (2) (1) Interest expense is a component of Other (income) expense, net.
Income Statement Effects of Derivatives Not Designated as Hedging Instruments	The table below provides information regarding the income statement effects of derivatives not designated as hedging instruments (including amounts attributable to discontinued operations): Amount of Derivative Pretax (Gain) Loss Recognized in Income Three Months Ended Six Months Ended ($ in millions) 2021 2020 2021 2020 Derivatives Not Designated as Hedging Instruments Income Statement Caption Foreign exchange contracts (1) Other (income) expense, net $ 167 $ 49 $ 217 $ (131) Foreign exchange contracts (2) Sales 14 4 10 (3) Interest rate contracts (3) Other (income) expense, net — 9 — 9 (1) These derivative contracts primarily mitigate changes in the value of remeasured foreign currency denominated monetary assets and liabilities attributable to changes in foreign currency exchange rates. Amounts in 2021 include a loss on forward exchange contracts entered into in conjunction with the spin-off of Organon. (2) These derivative contracts serve as economic hedges of forecasted transactions. (3) These derivative contracts serve as economic hedges against rising treasury rates.
Information on Investments in Debt and Equity Securities	Information on investments in debt and equity securities is as follows: June 30, 2021 December 31, 2020 Amortized Gross Unrealized Fair Amortized Gross Unrealized Fair ($ in millions) Gains Losses Gains Losses U.S. government and agency securities $ 82 $ — $ — $ 82 $ 84 $ — $ — $ 84 Corporate notes and bonds 4 — — 4 — — — — Foreign government bonds 2 — — 2 5 — — 5 Total debt securities $ 88 $ — $ — $ 88 $ 89 $ — $ — $ 89 Publicly traded equity securities (1) 1,579 1,787 Total debt and publicly traded equity securities $ 1,667 $ 1,876 (1) Unrealized net losses recorded in Other (income) expense, net on equity securities still held at June 30, 2021 were $18 million and $199 million in the second quarter and first six months of 2021, respectively. Unrealized net gains recorded in Other (income) expense, net on equity securities still held at June 30, 2020 were $464 million and $469 million in the second quarter and first six months of 2020, respectively.
Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis	Financial assets and liabilities measured at fair value on a recurring basis are summarized below: Fair Value Measurements Using Fair Value Measurements Using Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total ($ in millions) June 30, 2021 December 31, 2020 Assets Investments Foreign government bonds $ — $ 2 $ — $ 2 $ — $ 5 $ — $ 5 Publicly traded equity securities 409 — — 409 780 — — 780 409 2 — 411 780 5 — 785 Other assets (1) U.S. government and agency securities 82 — — 82 84 — — 84 Corporate notes and bonds 4 — — 4 — — — — Publicly traded equity securities 1,170 — — 1,170 1,007 — — 1,007 1,256 — — 1,256 1,091 — — 1,091 Derivative assets (2) Forward exchange contracts — 203 — 203 — 90 — 90 Purchased currency options — 94 — 94 — 37 — 37 Interest rate swaps — 36 — 36 — 55 — 55 — 333 — 333 — 182 — 182 Total assets $ 1,665 $ 335 $ — $ 2,000 $ 1,871 $ 187 $ — $ 2,058 Liabilities Other liabilities Contingent consideration $ — $ — $ 879 $ 879 $ — $ — $ 841 $ 841 Derivative liabilities (2) Forward exchange contracts — 173 — 173 — 505 — 505 Written currency options — 1 — 1 — 20 — 20 — 174 — 174 — 525 — 525 Total liabilities $ — $ 174 $ 879 $ 1,053 $ — $ 525 $ 841 $ 1,366 (1) Investments included in other assets are restricted as to use, including for the payment of benefits under employee benefit plans. (2) The fair value determination of derivatives includes the impact of the credit risk of counterparties to the derivatives and the Company’s own credit risk, the effects of which were not significant.
Information About the Changes in Liabilities for Contingent Consideration	Summarized information about the changes in liabilities for contingent consideration associated with business acquisitions is as follows: Six Months Ended June 30, ($ in millions) 2021 2020 Fair value January 1 $ 841 $ 767 Additions — 97 Changes in estimated fair value (1) 50 40 Payments — (106) Other (12) — Fair value June 30 (2)(3) $ 879 $ 798 (1) Recorded in Cost of sales, Research and development expenses, and Other (income) expense, net . Includes cumulative translation adjustments. (2) Balance at June 30, 2021 includes $297 million recorded as a current liability for amounts expected to be paid within the next 12 months. (3) At June 30, 2021 and December 31, 2020, $759 million and $711 million, respectively, of the liabilities relate to the termination of the Sanofi Pasteur MSD joint venture in 2016. As part of the termination, Merck recorded a liability for contingent future royalty payments of 11.5% on net sales of all Merck products that were previously sold by the joint venture through December 31, 2024. The fair value of this liability is determined utilizing the estimated amount and timing of projected cash flows using a risk-adjusted discount rate of 8% to present value the cash flows.

Inventories (Tables)

Inventories (Tables)	6 Months Ended
	Jun. 30, 2021
Inventory Disclosure [Abstract]
Schedule of Inventories	Inventories consisted of: ($ in millions) June 30, 2021 December 31, 2020 Finished goods $ 1,778 $ 1,610 Raw materials and work in process 5,954 5,949 Supplies 175 146 Total (approximates current cost) 7,907 7,705 Decrease to LIFO cost 4 (81) $ 7,911 $ 7,624 Recognized as: Inventories $ 5,499 $ 5,554 Other assets 2,412 2,070

Equity (Tables)

Equity (Tables)	6 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Equity	Three Months Ended June 30, Common Stock Other Retained Accumulated Treasury Stock Non- Total ($ and shares in millions except per share amounts) Shares Par Value Shares Cost Balance at April 1, 2020 3,577 $ 1,788 $ 39,697 $ 48,272 $ (6,391) 1,053 $ (57,161) $ 95 $ 26,300 Net income attributable to Merck & Co., Inc. — — — 3,002 — — — — 3,002 Other comprehensive loss, net of taxes — — — — (2) — — — (2) Cash dividends declared on common stock ($0.61 per share) — — — (1,550) — — — — (1,550) Share-based compensation plans and other — — (324) — — (5) 311 — (13) Net income attributable to noncontrolling interests — — — — — — — 8 8 Distributions attributable to noncontrolling interests — — — — — — — (1) (1) Balance at June 30, 2020 3,577 $ 1,788 $ 39,373 $ 49,724 $ (6,393) 1,048 $ (56,850) $ 102 $ 27,744 Balance at April 1, 2021 3,577 $ 1,788 $ 39,613 $ 48,888 $ (6,622) 1,046 $ (56,722) $ 94 $ 27,039 Net income attributable to Merck & Co., Inc. — — — 1,545 — — — — 1,545 Other comprehensive income, net of taxes — — — — 1,545 — — — 1,545 Cash dividends declared on common stock ($0.65 per share) — — — (1,656) — — — — (1,656) Treasury stock shares purchased — — — — — 3 (239) — (239) Spin-off of Organon & Co. — — 4,643 — 449 — — (1) 5,091 Share-based compensation plans and other — — (217) — — (5) 279 — 62 Net income attributable to noncontrolling interests — — — — — — — 1 1 Balance at June 30, 2021 3,577 $ 1,788 $ 44,039 $ 48,777 $ (4,628) 1,044 $ (56,682) $ 94 $ 33,388 Six Months Ended June 30, Common Stock Other Retained Accumulated Treasury Stock Non- Total ($ and shares in millions except per share amounts) Shares Par Value Shares Cost Balance at January 1, 2020 3,577 $ 1,788 $ 39,660 $ 46,602 $ (6,193) 1,038 $ (55,950) $ 94 $ 26,001 Net income attributable to Merck & Co., Inc. — — — 6,221 — — — — 6,221 Other comprehensive loss, net of taxes — — — — (200) — — — (200) Cash dividends declared on common stock ($1.22 per share) — — — (3,099) — — — — (3,099) Treasury stock shares purchased — — — — — 16 (1,281) — (1,281) Share-based compensation plans and other — — (287) — — (6) 381 — 94 Net income attributable to noncontrolling interests — — — — — — — 8 8 Balance at June 30, 2020 3,577 $ 1,788 $ 39,373 $ 49,724 $ (6,393) 1,048 $ (56,850) $ 102 $ 27,744 Balance at January 1, 2021 3,577 $ 1,788 $ 39,588 $ 47,362 $ (6,634) 1,047 $ (56,787) $ 87 $ 25,404 Net income attributable to Merck & Co., Inc. — — — 4,724 — — — — 4,724 Other comprehensive income, net of taxes — — — — 1,557 — — — 1,557 Cash dividends declared on common stock ($1.30 per share) — — — (3,309) — — — — (3,309) Treasury stock shares purchased — — — — — 3 (239) — (239) Spin-off of Organon & Co. — — 4,643 — 449 — — (1) 5,091 Share-based compensation plans and other — — (192) — — (6) 344 — 152 Net income attributable to noncontrolling interests — — — — — — — 8 8 Balance at June 30, 2021 3,577 $ 1,788 $ 44,039 $ 48,777 $ (4,628) 1,044 $ (56,682) $ 94 $ 33,388

Pension and Other Postretirem_2

Pension and Other Postretirement Benefit Plans (Tables)	6 Months Ended
	Jun. 30, 2021
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Components of net cost of defined benefit plans	The Company has defined benefit pension plans covering eligible employees in the U.S. and in certain of its international subsidiaries. The net periodic benefit cost of such plans (including certain costs reported as part of discontinued operations) consisted of the following components: Three Months Ended Six Months Ended 2021 2020 2021 2020 ($ in millions) U.S. International U.S. International U.S. International U.S. International Service cost $ 98 $ 87 $ 88 $ 73 $ 198 $ 179 $ 175 $ 146 Interest cost 106 30 109 33 202 59 217 68 Expected return on plan assets (191) (104) (195) (101) (379) (209) (388) (205) Amortization of unrecognized prior service credit (11) (4) (12) (3) (20) (9) (25) (6) Net loss amortization 58 38 76 31 142 78 152 62 Termination benefits 52 2 1 — 53 3 4 1 Curtailments 9 (27) — — 16 (27) 2 (1) Settlements — 2 9 2 — 2 9 2 $ 121 $ 24 $ 76 $ 35 $ 212 $ 76 $ 146 $ 67
Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Components of net cost of defined benefit plans	The Company provides medical benefits, principally to its eligible U.S. retirees and similar benefits to their dependents, through its other postretirement benefit plans. The net credit of such plans consisted of the following components: Three Months Ended Six Months Ended ($ in millions) 2021 2020 2021 2020 Service cost $ 13 $ 13 $ 26 $ 26 Interest cost 11 14 22 29 Expected return on plan assets (20) (19) (39) (37) Amortization of unrecognized prior service credit (25) (22) (50) (45) Termination benefits 37 — 37 — Curtailments (27) — (28) (1) $ (11) $ (14) $ (32) $ (28)

Other (Income) Expense, Net (Ta

Other (Income) Expense, Net (Tables)	6 Months Ended
	Jun. 30, 2021
Other Income and Expenses [Abstract]
Other (Income) Expense, Net	Other (income) expense, net, consisted of: Three Months Ended Six Months Ended ($ in millions) 2021 2020 2021 2020 Interest income $ (9) $ (14) $ (20) $ (39) Interest expense 202 209 401 421 Exchange losses 114 24 155 78 Income from investments in equity securities, net (1) (280) (551) (854) (603) Net periodic defined benefit plan (credit) cost other than service cost (110) (80) (199) (170) Other, net (20) 25 (41) (12) $ (103) $ (387) $ (558) $ (325)

Earnings Per Share (Tables)

Earnings Per Share (Tables)	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Calculations of Earnings Per Share	The calculations of earnings per share are as follows: Three Months Ended Six Months Ended ($ and shares in millions except per share amounts) 2021 2020 2021 2020 Net Income from Continuing Operations Attributable to Merck & Co., Inc. $ 1,213 $ 2,341 $ 3,958 $ 4,812 Income from Discontinued Operations, Net of Taxes and Amounts Attributable to Noncontrolling Interests 332 661 766 1,409 Net Income Attributable to Merck & Co., Inc. $ 1,545 $ 3,002 $ 4,724 $ 6,221 Average common shares outstanding 2,533 2,527 2,532 2,531 Common shares issuable (1) 7 9 8 11 Average common shares outstanding assuming dilution 2,540 2,536 2,540 2,542 Basic Earnings per Common Share Attributable to Merck & Co., Inc. Common Shareholders: Income from Continuing Operations $ 0.48 $ 0.93 $ 1.56 $ 1.90 Income from Discontinued Operations 0.13 0.26 0.30 0.56 Net Income $ 0.61 $ 1.19 $ 1.87 $ 2.46 Earnings per Common Share Assuming Dilution Attributable to Merck & Co., Inc. Common Shareholders: Income from Continuing Operations $ 0.48 $ 0.92 $ 1.56 $ 1.89 Income from Discontinued Operations 0.13 0.26 0.30 0.55 Net Income $ 0.61 $ 1.18 $ 1.86 $ 2.45 (1) Issuable primarily under share-based compensation plans.

Other Comprehensive Income (L_2

Other Comprehensive Income (Loss) (Tables)	6 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Changes in AOCI by Component	Changes in each component of other comprehensive income (loss) are as follows: Three Months Ended June 30, ($ in millions) Derivatives Investments Employee Foreign Currency Accumulated Other Balance April 1, 2020, net of taxes $ 135 $ — $ (4,201) $ (2,325) $ (6,391) Other comprehensive income (loss) before reclassification adjustments, pretax (110) — (21) 63 (68) Tax 23 — 6 16 45 Other comprehensive income (loss) before reclassification adjustments, net of taxes (87) — (15) 79 (23) Reclassification adjustments, pretax (42) (1) — 69 (3) — 27 Tax 9 — (15) — (6) Reclassification adjustments, net of taxes (33) — 54 — 21 Other comprehensive income (loss), net of taxes (120) — 39 79 (2) Balance June 30, 2020, net of taxes $ 15 $ — $ (4,162) $ (2,246) $ (6,393) Balance April 1, 2021, net of taxes $ (36) $ — $ (4,459) $ (2,127) $ (6,622) Other comprehensive income (loss) before reclassification adjustments, pretax (59) — 1,767 140 1,848 Tax 13 — (400) (8) (395) Other comprehensive income (loss) before reclassification adjustments, net of taxes (46) — 1,367 132 1,453 Reclassification adjustments, pretax 71 (1) — 55 (3) — 126 Tax (15) — (19) — (34) Reclassification adjustments, net of taxes 56 — 36 — 92 Other comprehensive income (loss), net of taxes 10 — 1,403 132 1,545 Spin-off of Organon (see Note 2) — — 28 421 449 Balance June 30, 2021, net of taxes $ (26) $ — $ (3,028) $ (1,574) $ (4,628) Six Months Ended June 30, ($ in millions) Derivatives Investments Employee Foreign Currency Accumulated Other Balance January 1, 2020, net of taxes $ 31 $ 18 $ (4,261) $ (1,981) $ (6,193) Other comprehensive income (loss) before reclassification adjustments, pretax 68 3 (21) (270) (220) Tax (14) — 11 5 2 Other comprehensive income (loss) before reclassification adjustments, net of taxes 54 3 (10) (265) (218) Reclassification adjustments, pretax (89) (1) (21) (2) 138 (3) — 28 Tax 19 — (29) — (10) Reclassification adjustments, net of taxes (70) (21) 109 — 18 Other comprehensive income (loss), net of taxes (16) (18) 99 (265) (200) Balance June 30, 2020, net of taxes $ 15 $ — $ (4,162) $ (2,246) $ (6,393) Balance January 1, 2021, net of taxes $ (266) $ — $ (4,540) $ (1,828) $ (6,634) Other comprehensive income (loss) before reclassification adjustments, pretax 121 — 1,763 (71) 1,813 Tax (25) — (401) (96) (522) Other comprehensive income (loss) before reclassification adjustments, net of taxes 96 — 1,362 (167) 1,291 Reclassification adjustments, pretax 182 (1) — 142 (3) — 324 Tax (38) — (20) — (58) Reclassification adjustments, net of taxes 144 — 122 — 266 Other comprehensive income (loss), net of taxes 240 — 1,484 (167) 1,557 Spin-off of Organon (see Note 2) — — 28 421 449 Balance June 30, 2021, net of taxes $ (26) $ — $ (3,028) $ (1,574) $ (4,628) (1) Primarily relates to foreign currency cash flow hedges that were reclassified from AOCI to Sales . (2) Represents net realized (gains) losses on the sales of available-for-sale debt securities that were reclassified from AOCI to Other (income) expense, net . (3) Includes net amortization of prior service cost and actuarial gains and losses included in net periodic benefit cost (see Note 11).

Segment Reporting (Tables)

Segment Reporting (Tables)	6 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Sales of Company's products	Sales of the Company’s products were as follows: Three Months Ended June 30, Six Months Ended June 30, 2021 2020 2021 2020 ($ in millions) U.S. Int’l Total U.S. Int’l Total U.S. Int’l Total U.S. Int’l Total Pharmaceutical: Oncology Keytruda $ 2,347 $ 1,829 $ 4,176 $ 2,043 $ 1,345 $ 3,388 $ 4,528 $ 3,548 $ 8,076 $ 3,949 $ 2,722 $ 6,672 Alliance revenue - Lynparza (1) 124 124 248 105 73 178 242 233 475 190 133 323 Alliance revenue - Lenvima (1) 88 93 181 98 53 151 173 137 310 188 91 279 Vaccines Gardasil/Gardasil 9 454 781 1,234 168 488 656 766 1,385 2,151 629 1,124 1,753 ProQuad/M-M-R II /Varivax 386 130 516 263 115 378 718 246 965 596 217 813 RotaTeq 111 97 208 100 68 168 229 137 366 241 150 391 Pneumovax 23 100 52 152 21 96 117 173 150 323 203 170 373 Vaqta 22 34 56 17 11 28 47 43 90 47 41 88 Hospital Acute Care Bridion 197 190 387 107 117 224 364 363 727 250 274 524 Prevymis 37 56 93 28 35 63 72 103 174 55 68 123 Noxafil 14 52 66 6 67 73 29 104 133 14 154 168 Primaxin — 60 60 1 63 64 — 125 125 1 114 115 Cancidas 1 53 54 (2) 45 43 3 108 111 1 98 98 Invanz (4) 52 48 — 43 43 — 104 104 6 102 108 Zerbaxa (2) 1 (1) 17 15 32 (4) (5) (9) 37 32 69 Immunology Simponi — 202 202 — 191 191 — 416 416 — 406 406 Remicade — 75 75 — 73 73 — 160 160 — 160 160 Neuroscience Belsomra 14 63 78 22 61 84 32 125 157 49 114 163 Virology Isentress/Isentress HD 74 118 192 76 120 196 145 256 401 151 290 441 Cardiovascular Alliance revenue-Adempas/Verquvo (2) 81 (7) 74 73 6 79 149 — 149 122 11 133 Adempas — 74 74 — 57 57 — 129 129 — 113 113 Diabetes Januvia 284 500 784 413 441 854 632 961 1,593 768 860 1,628 Janumet 74 403 477 143 348 490 158 805 962 256 737 993 Other pharmaceutical (3) 245 301 546 259 289 548 485 644 1,130 513 637 1,149 Total Pharmaceutical segment sales 4,647 5,333 9,980 3,958 4,220 8,178 8,941 10,277 19,218 8,266 8,818 17,083 Animal Health: Livestock 161 659 821 122 526 648 318 1,322 1,640 284 1,102 1,386 Companion Animals 298 353 651 220 233 453 578 672 1,250 442 486 928 Total Animal Health segment sales 459 1,012 1,472 342 759 1,101 896 1,994 2,890 726 1,588 2,314 Other segment sales (4) — — — — — — — — — 23 — 23 Total segment sales 5,106 6,345 11,452 4,300 4,979 9,279 9,837 12,271 22,108 9,015 10,406 19,420 Other (5) (6) (44) (50) 22 52 74 53 (132) (79) 38 182 221 $ 5,100 $ 6,301 $ 11,402 $ 4,322 $ 5,031 $ 9,353 $ 9,890 $ 12,139 $ 22,029 $ 9,053 $ 10,588 $ 19,641 U.S. plus international may not equal total due to rounding. (1) Alliance revenue represents Merck’s share of profits, which are product sales net of cost of sales and commercialization costs (see Note 4). (2) Alliance revenue represents Merck’s share of profits from sales in Bayer’s marketing territories, which are product sales net of cost of sales and commercialization costs (see Note 4). (3) Other pharmaceutical primarily reflects sales of other human health pharmaceutical products, including products within the franchises not listed separately. (4) Represents sales for the Healthcare Services segment. All the businesses in the Healthcare Services segment were fully divested in the first quarter of 2020.
Consolidated revenues by geographic area	Consolidated sales by geographic area where derived are as follows: Three Months Ended Six Months Ended ($ in millions) 2021 2020 2021 2020 United States $ 5,100 $ 4,322 $ 9,890 $ 9,053 Europe, Middle East and Africa 3,333 2,622 6,569 5,591 China 975 623 1,697 1,269 Japan 661 621 1,291 1,204 Asia Pacific (other than China and Japan) 594 489 1,168 1,015 Latin America 532 423 1,032 875 Other 207 253 382 634 $ 11,402 $ 9,353 $ 22,029 $ 19,641
Reconciliation of segment profits to income before taxes	A reconciliation of segment profits to Income from Continuing Operations Before Taxes is as follows: Three Months Ended Six Months Ended ($ in millions) 2021 2020 2021 2020 Segment profits: Pharmaceutical segment $ 7,257 $ 5,832 $ 13,845 $ 12,209 Animal Health segment 552 408 1,124 887 Other segment — — — 2 Total segment profits 7,809 6,240 14,969 13,098 Other profits (79) 43 (113) 163 Unallocated: Interest income 9 14 20 39 Interest expense (202) (209) (401) (421) Amortization (357) (599) (871) (988) Depreciation (332) (367) (673) (733) Research and development (4,175) (1,956) (6,480) (4,020) Restructuring costs (82) (82) (380) (152) Other unallocated, net (874) (343) (1,367) (1,284) $ 1,717 $ 2,741 $ 4,704 $ 5,702

Spin-Off of Organon & Co. - Nar

Spin-Off of Organon & Co. - Narrative (Details) shares in Thousands, $ in Millions	Jun. 02, 2021USD ($)shares	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Distribution from Organon & Co.	$ 9,000
Disposal group, other expense		$ 307	$ 120	$ 556	$ 290
Stock options, converted awards (in shares) | shares	1,900
Disposal group, including discontinued operations, liabilities	$ 5,100
Disposal group, including discontinued operations, debt	9,400
Goodwill	1,400					$ 1,356
Property, plant and equipment, net	981					986
Disposal group, including discontinued operation, cash	929
Inventories	815					756
Other intangibles, net	519					$ 503
Disposal group, including discontinued operation, other liabilities	$ 328
Spin-off of Organon & Co.		5,091		5,091
Accumulated Other Comprehensive Loss
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Spin-off of Organon & Co.		449		449
Foreign Currency Translation Adjustment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Spin-off of Organon & Co.		421		421
Employee Benefit Plans
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Spin-off of Organon & Co.		28		28
Other Paid-In Capital
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Spin-off of Organon & Co.		4,643		4,643
Restricted Stock Units (RSUs)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity instruments other than options, converted awards (in shares) | shares	1,300
Performance Share Units (PSUs)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity instruments other than options, converted awards (in shares) | shares	248
Organon & Co.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Stock conversion ratio	0.1
Due from related parties, current		1,600		1,600
Due to related parties, current		$ 1,000		$ 1,000
Maximum | Transition services agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Period of continuing involvement after disposal	25 months
Maximum | Manufacturing and supply agreements
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Period of continuing involvement after disposal	10 years
Minimum | Manufacturing and supply agreements
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Period of continuing involvement after disposal	4 years
Organon & Co.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Face amount of debt	$ 9,500

Spin-Off of Organon & Co. - Sch

Spin-Off of Organon & Co. - Schedule of Disposal Groups in Discontinued Operations (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Jun. 02, 2021	Dec. 31, 2020
Discontinued Operations and Disposal Groups [Abstract]
Sales	$ 1,059	$ 1,519	$ 2,512	$ 3,288
Cost of sales	318	412	789	895
Selling, general and administrative	431	293	877	657
Research and development	50	38	103	72
Restructuring costs	0	1	1	3
Other (income) expense, net	(23)	(4)	(15)	4
Operating expenses	776	740	1,755	1,631
Income from discontinued operations before taxes	283	779	757	1,657
Tax (benefit) provision	(49)	114	(12)	239
Income from discontinued operations, net of taxes	332	665	769	1,418
Less: Income of discontinued operations attributable to noncontrolling interests	0	4	3	9
Income from Discontinued Operations, Net of Taxes and Amounts Attributable to Noncontrolling Interests	332	$ 661	766	$ 1,409
Cash and cash equivalents						$ 12
Accounts receivable, less allowance for doubtful accounts						1,048
Inventories					$ 815	756
Other current assets						867
Current assets of discontinued operations	0		0			2,683
Property, plant and equipment, net					981	986
Goodwill					1,400	1,356
Other intangibles, net					$ 519	503
Other assets						330
Noncurrent Assets of Discontinued Operations	0		0			3,175
Trade accounts payable						267
Accrued and other current liabilities						841
Income taxes payable						(22)
Current liabilities of discontinued operations	0		0			1,086
Deferred income taxes						10
Other noncurrent liabilities						176
Noncurrent Liabilities of Discontinued Operations	$ 0		$ 0			$ 186

Acquisitions, Research Collab_3

Acquisitions, Research Collaborations and License Agreements - Acquisitions (Details) - USD ($) $ in Millions	Jan. 16, 2020	Apr. 30, 2021	Mar. 31, 2021	Jan. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Contingent consideration					$ 841	$ 798	$ 879	$ 798	$ 879	$ 798	$ 841	$ 767
Goodwill					18,882		18,873		18,873		18,882
Research and development							4,321	2,085	6,732	4,260
Inventories					5,554		5,499		5,499		5,554
Payments to Acquire Productive Assets									2,068	1,553
Changes in estimated fair value									50	40
OncoImmune
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Payment to acquire business					423
Other assets and liabilities, net					(22)						$ (22)
Payments to Acquire Investments					$ 50
Equity Method Investment, Ownership Percentage					20.00%						20.00%
Investments					$ 33						$ 33
Premium on shares acquired					$ 17
Research and Development Asset Acquired Other than Through Business Combination, Written-off											462
COVID-19
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Charges related to program discontinuation							$ 37		$ 207
Pandion Therapeutics
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Payment to acquire business		$ 1,900
Transaction costs		147
Other assets and liabilities, net		(156)
Research and development		$ 1,700
Themis
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Payment to acquire business						366
Contingent consideration						85		85		85
IPR&D						113		113		113
Cash and cash equivalents						59		59		59
Goodwill						239		239		239
Other assets and liabilities, net						(32)		(32)		(32)
Deferred tax assets						72		72		72
Contingent consideration, maximum						740		740		740
Business Combination, Contingent Consideration Arrangements, Change in Range of Outcomes, Contingent Consideration, Liability, Value, High											450
Themis | COVID-19
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)											90
Changes in estimated fair value											$ 45
ArQule
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Payment to acquire business	$ 2,700
IPR&D	2,280
Share-based compensation payments attributable to precombination service	138
Transaction costs	95
Cash and cash equivalents	145
Goodwill	512
Other assets and liabilities, net	34
Deferred income tax liabilities	361
Intangible assets	$ 80
Development Milestones | Themis
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Contingent consideration, maximum						60		60		60
Sales-Based Milestones | Themis
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Contingent consideration, maximum						194		194		194
Regulatory Milestones | Themis
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Contingent consideration, maximum						$ 196		$ 196		$ 196
Gilead Sciences | oral and injectable formulations programs | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
proft share			40.00%
profit share counterparty			60.00%
Gilead Sciences | oral formulation | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
proft share			35.00%
profit share counterparty			65.00%
Sales threshold			$ 2,000
Gilead Sciences | injectable formulation | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
proft share			35.00%
profit share counterparty			65.00%
Sales threshold			$ 3,500
Artiva Biotherapeutics, Inc. | Licensing Agreements
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Upfront and milestone payments				$ 30
Upfront and milestone payments to be made				$ 15
Artiva Biotherapeutics, Inc. | Minimum | Licensing Agreements
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Royalty Rate, Percentage				7.00%
Artiva Biotherapeutics, Inc. | Maximum | Licensing Agreements
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Royalty Rate, Percentage				14.00%
Artiva Biotherapeutics, Inc. | Development Milestones | Licensing Agreements
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Contingent milestone payments collaborative arrangement				$ 217.5
Artiva Biotherapeutics, Inc. | Sales-Based Milestones | Licensing Agreements
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Contingent milestone payments collaborative arrangement				1,050
Artiva Biotherapeutics, Inc. | Regulatory Milestones | Licensing Agreements
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Contingent milestone payments collaborative arrangement				$ 570

Acquisitions, Research Collab_4

Acquisitions, Research Collaborations and License Agreements - Values of Assets Acquired and Liabilities Assumed, ArQule (Details) $ in Millions	Jun. 30, 2021USD ($)	Dec. 31, 2020USD ($)	Jan. 16, 2020USD ($)
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Goodwill	$ 18,873	$ 18,882
ArQule
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Cash and cash equivalents			$ 145
IPR&D			2,280
Intangible assets			80
Deferred income tax liabilities			(361)
Other assets and liabilities, net			34
Total identifiable net assets			2,178
Goodwill			512
Consideration transferred			$ 2,690
ArQule | Measurement Input, Discount Rate
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Present value discount rate			0.125

Collaborative Arrangements - Na

Collaborative Arrangements - Narrative (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development		$ 4,321	$ 2,085	$ 6,732	$ 4,260
Other liabilities, noncurrent		9,872		9,872		$ 12,306
Amortization				871	$ 988
Lynparza | Other Assets
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Finite-lived intangible assets		1,200		1,200
Lenvima | Other Assets
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Finite-lived intangible assets		1,000		1,000
Adempas | Other intangible assets
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Finite-lived intangible assets		920		920
Verquvo
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Amortization				153
Verquvo | Other intangible assets
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Finite-lived intangible assets		75		75
AstraZeneca | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | Lynparza
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential Future Milestone Payments Sales-Based		2,700		2,700
Milestone Payments Accrued Sales Based		400		400
Potential Future Milestone Payments Regulatory		1,400		1,400
Eisai
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
License option payment related to collaborative arrangement	$ 125
Eisai | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement | Lenvima
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential Future Milestone Payments Sales-Based		2,600		2,600
Milestone Payments Sales-Based				200
Milestone Payments Accrued Sales Based		600		600
Potential Future Milestone Payments Regulatory		125		125
Bayer AG | Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Liabilities		400		400
Milestone Payments Accrued Sales Based		$ 400		$ 400

Collaborative Arrangements - Sc

Collaborative Arrangements - Schedule of Transactions (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sales	$ 11,402	$ 9,353	$ 22,029	$ 19,641
Cost of sales	3,104	2,747	6,303	5,576
Selling, general and administrative	2,281	2,085	4,468	4,276
Research and development	4,321	2,085	6,732	4,260
Payables, current	21,906		21,906		$ 27,327
Other current assets | AstraZeneca | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Receivables from Bayer included in Other current assets	258		258		215
Other current assets | Eisai | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Receivables from Bayer included in Other current assets	212		212		157
Other current assets | Bayer AG | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Receivables from Bayer included in Other current assets	65		65		65
Accounts payable and accrued liabilities | AstraZeneca | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payables, current	418		418		423
Accounts payable and accrued liabilities | Eisai | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payables, current	600		600		335
Other Noncurrent Liabilities | Eisai | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payables to Bayer included in Other Noncurrent Liabilities	0		0		600
Other Noncurrent Liabilities | Bayer AG | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payables to Bayer included in Other Noncurrent Liabilities	400		400		$ 0
Revenue | AstraZeneca | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Alliance revenue - profit sharing	256	178	489	323
Revenue | AstraZeneca | Collaborative Arrangement | Alliance revenue - Lynparza (1)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Alliance revenue - profit sharing	248	178	475	323
Revenue | AstraZeneca | Collaborative Arrangement | Alliance revenue - Koselugo
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Alliance revenue - profit sharing	8	0	14	0
Revenue | Eisai | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Alliance revenue - profit sharing	181	151	310	279
Revenue | Bayer AG | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Alliance revenue - profit sharing	74	79	149	133
Sales	149	136	279	246
Revenue | Bayer AG | Collaborative Arrangement | Adempas
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaborative Arrangement, Sales, Net	74	57	129	113
Revenue | Bayer AG | Collaborative Arrangement | Verquvo
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaborative Arrangement, Sales, Net	1	0	1	0
Cost of sales | AstraZeneca | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cost of sales	42	137	84	164
Cost of sales | Eisai | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cost of sales	47	135	94	170
Cost of sales | Bayer AG | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cost of sales	39	28	229	57
Amortization of intangible assets	153
Selling, general and administrative | AstraZeneca | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Selling, general and administrative	43	39	83	72
Selling, general and administrative | Eisai | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Selling, general and administrative	31	19	54	31
Selling, general and administrative | Bayer AG | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Selling, general and administrative	32	17	58	28
Research and development | AstraZeneca | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development	31	37	60	73
Research and development | Eisai | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development	57	56	121	120
Research and development | Bayer AG | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development	$ 13	$ 16	$ 20	$ 41

Restructuring - Narrative (Deta

Restructuring - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2021
Restructuring Cost and Reserve [Line Items]
Cumulative costs since program inception	$ 2,300		$ 2,300
Estimate of cumulative pre tax costs that will result in cash outlays			70.00%
Estimate of cumulative pre tax costs that will be noncash			30.00%
Expected restructuring and related cost	3,000		$ 3,000
Total pretax restructuring costs	$ 128	$ 149	$ 462	$ 315
Forecast
Restructuring Cost and Reserve [Line Items]
Expected restructuring and related cost					$ 700

Restructuring - Charges Activit

Restructuring - Charges Activities by Type of Cost (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	$ 128	$ 149	$ 462	$ 315
Separation Costs
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	64	35	293	82
Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	19	73	38	126
Other
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	45	41	131	107
Cost of sales
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	38	25	65	93
Cost of sales | Separation Costs
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	0	0	0	0
Cost of sales | Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	11	31	21	56
Cost of sales | Other
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	27	(6)	44	37
Selling, general and administrative
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	2	11	4	22
Selling, general and administrative | Separation Costs
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	0	0	0	0
Selling, general and administrative | Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	2	11	4	22
Selling, general and administrative | Other
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	0	0	0	0
Research and development
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	6	31	13	48
Research and development | Separation Costs
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	0	0	0	0
Research and development | Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	6	31	13	48
Research and development | Other
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	0	0	0	0
Restructuring costs
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	82	82	380	152
Restructuring costs | Separation Costs
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	64	35	293	82
Restructuring costs | Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	0	0	0	0
Restructuring costs | Other
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	$ 18	$ 47	$ 87	$ 70

Restructuring - Activities by P

Restructuring - Activities by Program (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			$ 586
Expense	$ 128	$ 149	462	$ 315
(Payments) receipts, net			(387)
Non-cash activity			10
Restructuring reserve, ending balance	671		671
Separation Costs
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			567
Expense	64	35	293	82
(Payments) receipts, net			(230)
Non-cash activity			0
Restructuring reserve, ending balance	630		630
Accelerated Depreciation
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			0
Expense	19	73	38	126
(Payments) receipts, net			0
Non-cash activity			(38)
Restructuring reserve, ending balance	0		0
Other
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			19
Expense	45	$ 41	131	$ 107
(Payments) receipts, net			(157)
Non-cash activity			48
Restructuring reserve, ending balance	$ 41		$ 41

Financial Instruments - Narrati

Financial Instruments - Narrative (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2021USD ($)interest_rate_swap	Mar. 31, 2021USD ($)	Jun. 30, 2021USD ($)interest_rate_swap	Jun. 30, 2020USD ($)	Jan. 31, 2021USD ($)interest_rate_swap	Dec. 31, 2020USD ($)
Derivative [Line Items]
Pretax net unrealized losses on derivatives maturing within next 12 months estimated to be reclassified from AOCI to sales			$ 52,000,000
Equity investments without readily determinable fair values	$ 694,000,000		694,000,000	$ 487,000,000
Unrealized gains recognized on investments in equity securities without readily determinable fair value			75,000,000	18,000,000
Cumulative unrealized gains on investments	244,000,000		244,000,000
Cumulative unrealized losses on investments	8,000,000		8,000,000
Payments of contingent consideration			0	106,000,000
Fair value of loans payable and long-term debt, including current portion	29,500,000,000		29,500,000,000			$ 36,000,000,000
Debt, carrying amount	26,500,000,000		26,500,000,000			31,800,000,000
Accounts Receivable, Sale	2,400,000,000	$ 2,100,000,000
Cash collateral received from counterparties	13,000,000		13,000,000			0
Cash collateral advanced to counterparties	0		0			36,000,000
Total swap notional amount	29,426,000,000		29,426,000,000			32,784,000,000
Unrealized losses recognized on investments in equity securities without readily determinable fair values			1,000,000	$ 3,000,000
Level 2
Derivative [Line Items]
Cash equivalents	7,500,000,000		7,500,000,000			6,800,000,000
Derivatives Designated as Hedging Instruments
Derivative [Line Items]
Total swap notional amount	12,755,000,000		$ 12,755,000,000			13,714,000,000
Derivatives Designated as Hedging Instruments | Maximum
Derivative [Line Items]
Maximum average period of maturities of contracts in years (less than)			2 years
Derivatives Not Designated as Hedging Instruments
Derivative [Line Items]
Total swap notional amount	$ 16,671,000,000		$ 16,671,000,000			$ 19,070,000,000
Derivatives Not Designated as Hedging Instruments | Maximum
Derivative [Line Items]
Maximum average period of maturities of contracts in years (less than)			1 year
3.875% Notes Due 2021 [Member]
Derivative [Line Items]
Face amount of debt					$ 1,150,000,000
Stated interest rate (as percent)					3.875%
Interest rate swap contracts
Derivative [Line Items]
Number of interest rate swaps held (in interest rate swaps) | interest_rate_swap	9		9		5
Total swap notional amount					$ 1,150,000,000

Financial Instruments - Effect

Financial Instruments - Effect of Net Investment Hedges (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Pretax (Gain) Loss Recognized in Other Comprehensive Income	$ (3)	$ 8	$ (28)	$ 5
Foreign exchange contracts | Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Pretax (Gain) Loss Recognized in Other (income) expense, net for Amounts Excluded from Effectiveness Testing	(4)	(4)	(8)	(11)
Euro-denominated notes
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Pretax (Gain) Loss Recognized in Other Comprehensive Income	45	72	(122)	21
Euro-denominated notes | Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Pretax (Gain) Loss Recognized in Other (income) expense, net for Amounts Excluded from Effectiveness Testing	$ 0	$ 0	$ 0	$ 0

Financial Instruments - Summary

Financial Instruments - Summary of Interest Rate Swaps Held (Details)	Jun. 30, 2021USD ($)interest_rate_swap	Jan. 31, 2021USD ($)interest_rate_swap	Dec. 31, 2020USD ($)
Derivative [Line Items]
Total swap notional amount	$ 29,426,000,000		$ 32,784,000,000
Interest rate swap contracts
Derivative [Line Items]
Number of Interest Rate Swaps Held (in interest rate swaps) | interest_rate_swap	9	5
Total swap notional amount		$ 1,150,000,000
2.40% notes due 2022 | Interest rate swap contracts
Derivative [Line Items]
Stated interest rate (as percent)	2.40%
Par Value of Debt	$ 1,000,000,000
Number of Interest Rate Swaps Held (in interest rate swaps) | interest_rate_swap	4
Total swap notional amount	$ 1,000,000,000
2.35% notes due 2022 | Interest rate swap contracts
Derivative [Line Items]
Stated interest rate (as percent)	2.35%
Par Value of Debt	$ 1,250,000,000
Number of Interest Rate Swaps Held (in interest rate swaps) | interest_rate_swap	5
Total swap notional amount	$ 1,250,000,000

Financial Instruments - Fair Va

Financial Instruments - Fair Value Hedges (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Loans payable and current portion of long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Hedged Liabilities	$ 1,261	$ 1,150
Cumulative Amount of Fair Value Hedging Adjustment Increase (Decrease) Included in the Carrying Amount	11	0
Long-Term Debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Hedged Liabilities	1,022	2,301
Cumulative Amount of Fair Value Hedging Adjustment Increase (Decrease) Included in the Carrying Amount	$ 23	$ 53

Financial Instruments - Fair _2

Financial Instruments - Fair Value of Derivatives Segregated between those Derivatives that are Designated as Hedging Instruments and those that are Not Designated as Hedging Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	$ 333	$ 182
Fair Value of Derivative, Liability	174	525
U.S Dollar Notional Amount	29,426	32,784
Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	241	112
Fair Value of Derivative, Liability	41	218
U.S Dollar Notional Amount	12,755	13,714
Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	92	70
Fair Value of Derivative, Liability	133	307
U.S Dollar Notional Amount	16,671	19,070
Interest Rate Contract | Derivatives Designated as Hedging Instruments | Other current assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	12	1
U.S Dollar Notional Amount	1,250	1,150
Interest Rate Contract | Derivatives Designated as Hedging Instruments | Other Assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	24	54
U.S Dollar Notional Amount	1,000	2,250
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Other current assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	156	12
U.S Dollar Notional Amount	5,970	3,183
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Other Assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	49	45
U.S Dollar Notional Amount	1,601	2,030
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	40	217
U.S Dollar Notional Amount	2,850	5,049
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	1	1
U.S Dollar Notional Amount	84	52
Foreign exchange contracts | Derivatives Not Designated as Hedging Instruments | Other current assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	92	70
U.S Dollar Notional Amount	6,981	7,260
Foreign exchange contracts | Derivatives Not Designated as Hedging Instruments | Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	133	307
U.S Dollar Notional Amount	$ 9,690	$ 11,810

Financial Instruments - Informa

Financial Instruments - Information on Derivative Positions Subject to Master Netting Arrangements as if they were Presented on a Net Basis (Details) - USD ($)	Jun. 30, 2021	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross amounts recognized in the consolidated balance sheet, asset	$ 333,000,000	$ 182,000,000
Gross amount subject to offset in master netting arrangements not offset in the condensed balance sheet, asset	(152,000,000)	(156,000,000)
Cash collateral received, asset	(13,000,000)	0
Net amounts, asset	168,000,000	26,000,000
Gross amounts recognized in the consolidated balance sheet, liability	174,000,000	525,000,000
Gross amount subject to offset in master netting arrangements not offset in the condensed balance sheet, liability	(152,000,000)	(156,000,000)
Cash collateral received, liability	0	(36,000,000)
Net amounts, liability	$ 22,000,000	$ 333,000,000

Financial Instruments - Locatio

Financial Instruments - Location and Amount of Pretax (Gains) Losses of Derivatives (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Sales	$ 11,402	$ 9,353	$ 22,029	$ 19,641
Other (income) expense, net	(103)	(387)	(558)	(325)
Other comprehensive income (loss)	1,545	(2)	1,557	(200)
Interest rate swap contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain recognized in OCI on derivatives	0	(1)	(1)	(2)
Interest rate swap contracts | Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Hedged items	(9)	1	(19)	68
Derivatives designated as hedging instruments	(1)	(8)	0	(76)
Amount of gain recognized in Other (income) expense, net on derivatives	0	(1)	(1)	(2)
Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain recognized in OCI on derivatives	(58)	(109)	121	69
(Decrease) increase in Sales as a result of AOCI reclassifications	71	(42)	183	(88)
Foreign exchange contracts | Reclassification out of Accumulated Other Comprehensive Income | Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest
Derivative Instruments, Gain (Loss) [Line Items]
Sales	$ (71)	$ 42	$ (183)	$ 88

Financial Instruments - Income

Financial Instruments - Income Statement Effects on Derivatives Not Designated as Hedging Instruments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Foreign currency | Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Derivative Pretax (Gain) Loss Recognized in Income	$ 167	$ 49	$ 217	$ (131)
Forecasted transactions | Sales
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Derivative Pretax (Gain) Loss Recognized in Income	14	4	10	(3)
Interest Rate Contract | Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Derivative Pretax (Gain) Loss Recognized in Income	$ 0	$ 9	$ 0	$ 9

Financial Instruments - Infor_2

Financial Instruments - Information on Available-for-sale Investments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	$ 88		$ 88		$ 89
Debt securities, unrealized gains	0		0		0
Debt securities, unrealized losses	0		0		0
Debt securities, fair value	88		88		89
Publicly traded equity securities, fair value	1,579		1,579		1,787
Total debt and publicly traded equity securities, fair value	1,667		1,667		1,876
Unrealized net losses (gains)	(18)	$ 464	(199)	$ 469
Unrealized losses recognized on investments in equity securities without readily determinable fair values			1	$ 3
U.S. government and agency securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	82		82		84
Debt securities, unrealized gains	0		0		0
Debt securities, unrealized losses	0		0		0
Debt securities, fair value	82		82		84
Foreign government bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	2		2		5
Debt securities, unrealized gains	0		0		0
Debt securities, unrealized losses	0		0		0
Debt securities, fair value	2		2		5
Corporate notes and bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	4		4		0
Debt securities, unrealized gains	0		0		0
Debt securities, unrealized losses	0		0		0
Debt securities, fair value	$ 4		$ 4		$ 0

Financial Instruments - Financi

Financial Instruments - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Assets
Investments	$ 88	$ 89
Publicly traded equity securities	1,579	1,787
Derivative assets	333	182
Liabilities
Contingent consideration	879	841	$ 798	$ 767
Derivative liabilities	174	525
Foreign government bonds
Assets
Investments	2	5
Corporate notes and bonds
Assets
Investments	4	0
U.S. government and agency securities
Assets
Investments	82	84
Fair Value, Measurements, Recurring
Assets
Investments	411	785
Other assets	1,256	1,091
Derivative assets	333	182
Total assets	2,000	2,058
Liabilities
Contingent consideration	879	841
Derivative liabilities	174	525
Total liabilities	1,053	1,366
Fair Value, Measurements, Recurring | Foreign exchange contracts
Assets
Derivative assets	203	90
Liabilities
Derivative liabilities	173	505
Fair Value, Measurements, Recurring | Interest rate swap contracts
Assets
Derivative assets	36	55
Fair Value, Measurements, Recurring | Currency options
Assets
Derivative assets	94	37
Liabilities
Derivative liabilities	1	20
Fair Value, Measurements, Recurring | Level 1
Assets
Investments	409	780
Other assets	1,256	1,091
Derivative assets	0	0
Total assets	1,665	1,871
Liabilities
Contingent consideration	0	0
Derivative liabilities	0	0
Total liabilities	0	0
Fair Value, Measurements, Recurring | Level 1 | Foreign exchange contracts
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Level 1 | Interest rate swap contracts
Assets
Derivative assets	0	0
Fair Value, Measurements, Recurring | Level 1 | Currency options
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Level 2
Assets
Investments	2	5
Other assets	0	0
Derivative assets	333	182
Total assets	335	187
Liabilities
Contingent consideration	0	0
Derivative liabilities	174	525
Total liabilities	174	525
Fair Value, Measurements, Recurring | Level 2 | Foreign exchange contracts
Assets
Derivative assets	203	90
Liabilities
Derivative liabilities	173	505
Fair Value, Measurements, Recurring | Level 2 | Interest rate swap contracts
Assets
Derivative assets	36	55
Fair Value, Measurements, Recurring | Level 2 | Currency options
Assets
Derivative assets	94	37
Liabilities
Derivative liabilities	1	20
Fair Value, Measurements, Recurring | Level 3
Assets
Investments	0	0
Other assets	0	0
Derivative assets	0	0
Total assets	0	0
Liabilities
Contingent consideration	879	841
Derivative liabilities	0	0
Total liabilities	879	841
Fair Value, Measurements, Recurring | Level 3 | Foreign exchange contracts
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Level 3 | Interest rate swap contracts
Assets
Derivative assets	0	0
Fair Value, Measurements, Recurring | Level 3 | Currency options
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Foreign government bonds
Assets
Investments	2	5
Fair Value, Measurements, Recurring | Foreign government bonds | Level 1
Assets
Investments	0	0
Fair Value, Measurements, Recurring | Foreign government bonds | Level 2
Assets
Investments	2	5
Fair Value, Measurements, Recurring | Foreign government bonds | Level 3
Assets
Investments	0	0
Fair Value, Measurements, Recurring | Corporate notes and bonds
Assets
Other assets	4	0
Fair Value, Measurements, Recurring | Corporate notes and bonds | Level 1
Assets
Other assets	4	0
Fair Value, Measurements, Recurring | Corporate notes and bonds | Level 2
Assets
Other assets	0	0
Fair Value, Measurements, Recurring | Corporate notes and bonds | Level 3
Assets
Other assets	0	0
Fair Value, Measurements, Recurring | U.S. government and agency securities
Assets
Other assets	82	84
Fair Value, Measurements, Recurring | U.S. government and agency securities | Level 1
Assets
Other assets	82	84
Fair Value, Measurements, Recurring | U.S. government and agency securities | Level 2
Assets
Other assets	0	0
Fair Value, Measurements, Recurring | U.S. government and agency securities | Level 3
Assets
Other assets	0	0
Fair Value, Measurements, Recurring | Publicly traded equity securities
Assets
Publicly traded equity securities	409	780
Other assets	1,170	1,007
Fair Value, Measurements, Recurring | Publicly traded equity securities | Level 1
Assets
Publicly traded equity securities	409	780
Other assets	1,170	1,007
Fair Value, Measurements, Recurring | Publicly traded equity securities | Level 2
Assets
Publicly traded equity securities	0	0
Other assets	0	0
Fair Value, Measurements, Recurring | Publicly traded equity securities | Level 3
Assets
Publicly traded equity securities	0	0
Other assets	$ 0	$ 0

Financial Instruments - Infor_3

Financial Instruments - Information About Changes in Liabilities for Contingent Consideration (Details) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	$ 841	$ 767	$ 767
Additions	0	97
Changes in estimated fair value	50	40
Payments	0	(106)
Other	(12)	0
Fair value, ending balance	879	798	841
Current liability	297
Contingent consideration	879	$ 798	841
Sanofi Pasteur
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	711
Fair value, ending balance	759		711
Contingent consideration	$ 759		$ 711
Contingent consideration, measurement input, discount rate (as percent)	0.115
Measurement Input, Discount Rate | Sanofi Pasteur
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent consideration, measurement input, discount rate (as percent)	0.08

Inventories - Inventories (Deta

Inventories - Inventories (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Inventory Disclosure [Abstract]
Finished goods	$ 1,778	$ 1,610
Raw materials and work in process	5,954	5,949
Supplies	175	146
Total (approximates current cost)	7,907	7,705
Decrease to LIFO cost	4	(81)
Total current and noncurrent inventories	7,911	7,624
Recognized as:
Inventories	5,499	5,554
Other assets	$ 2,412	$ 2,070

Inventories - Narrative (Detail

Inventories - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Inventory [Line Items]
Inventories classified in Other assets	$ 2,412	$ 2,070
Inventories Not Expected to be Sold Within One Year
Inventory [Line Items]
Inventories classified in Other assets	1,700	1,800
Inventories Produced in Preparation for Product Launches
Inventory [Line Items]
Inventories classified in Other assets	$ 681	$ 279

Intangible Assets, Goodwill and

Intangible Assets, Goodwill and Other (Details) - USD ($) $ in Millions	Jun. 02, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 1,400	$ 1,356
Other intangibles, net	519	$ 503
Technology Rights
Finite-Lived Intangible Assets [Line Items]
Other intangibles, net	394
License
Finite-Lived Intangible Assets [Line Items]
Other intangibles, net	$ 125

Contingencies - Narrative (Deta

Contingencies - Narrative (Details) $ in Millions	1 Months Ended	6 Months Ended
	Mar. 31, 2014Case	Jun. 30, 2021USD ($)ClaimCase	Dec. 31, 2020USD ($)
Legal Defense Costs
Loss Contingencies [Line Items]
Legal defense costs reserve | $		$ 230	$ 235
Zetia antitrust litigation
Loss Contingencies [Line Items]
Loss contingency, pending claims, number (in legal matters) | Claim		35
Fosamax
Loss Contingencies [Line Items]
Loss contingency, pending claims, number (in legal matters)		3,475
Fosamax | Femur Fracture Litigation | Federal
Loss Contingencies [Line Items]
Loss contingency, claims dismissed, number (in legal matters)	650
Loss contingency, claims on appeal, number (in legal matters)	515
Januvia
Loss Contingencies [Line Items]
Loss contingency, pending claims, number (in legal matters) | Claim		1,470
Januvia | Other state courts
Loss Contingencies [Line Items]
Loss contingency, pending claims, number (in legal matters) | Claim		6
Januvia | Cases Company Agreed To Toll Statute Of Limitations
Loss Contingencies [Line Items]
Loss contingency, pending claims, number (in legal matters) | Claim		50
Bridion | Patents
Loss Contingencies [Line Items]
Loss Contingency, Claims Settled, Number		2
Januvia and Janumet | Patents
Loss Contingencies [Line Items]
Loss Contingency, Claims Settled, Number		10

Equity - Rollforward Reconcilia

Equity - Rollforward Reconciliations (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, beginning balance (in shares)			3,577,103,522
Equity, beginning balance	$ 27,039	$ 26,300	$ 25,404	$ 26,001
Net income attributable to Merck & Co., Inc.	1,545	3,002	4,724	6,221
Other comprehensive income (loss), net of taxes	1,545	(2)	1,557	(200)
Cash dividends declared on common stock	(1,656)	(1,550)	(3,309)	(3,099)
Treasury stock shares purchased	(239)		(239)	(1,281)
Spin-off of Organon & Co.	5,091		5,091
Share-based compensation plans and other	62	(13)	152	94
Distributions attributable to noncontrolling interests		(1)
Net income (loss) attributable to noncontrolling interests	$ 1	8	$ 8	8
Shares, ending balance (in shares)	3,577,103,522		3,577,103,522
Equity, ending balance	$ 33,388	$ 27,744	$ 33,388	$ 27,744
Cash dividends declared on common stock (in dollars per share)	$ 0.65	$ 0.61	$ 1.30	$ 1.22
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, beginning balance (in shares)	3,577,000,000	3,577,000,000	3,577,000,000	3,577,000,000
Equity, beginning balance	$ 1,788	$ 1,788	$ 1,788	$ 1,788
Shares, ending balance (in shares)	3,577,000,000	3,577,000,000	3,577,000,000	3,577,000,000
Equity, ending balance	$ 1,788	$ 1,788	$ 1,788	$ 1,788
Other Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning balance	39,613	39,697	39,588	39,660
Treasury stock shares purchased				0
Spin-off of Organon & Co.	4,643		4,643
Share-based compensation plans and other	(217)	(324)	(192)	(287)
Equity, ending balance	44,039	39,373	44,039	39,373
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning balance	48,888	48,272	47,362	46,602
Net income attributable to Merck & Co., Inc.	1,545	3,002	4,724	6,221
Cash dividends declared on common stock	(1,656)	(1,550)	(3,309)	(3,099)
Equity, ending balance	48,777	49,724	48,777	49,724
Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning balance	(6,622)	(6,391)	(6,634)	(6,193)
Other comprehensive income (loss), net of taxes	1,545	(2)	1,557	(200)
Spin-off of Organon & Co.	449		449
Equity, ending balance	$ (4,628)	$ (6,393)	$ (4,628)	$ (6,393)
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, beginning balance (in shares)	1,046,000,000	1,053,000,000	1,047,000,000	1,038,000,000
Equity, beginning balance	$ (56,722)	$ (57,161)	$ (56,787)	$ (55,950)
Treasury stock shares purchased (in shares)	3,000,000		3,000,000	16,000,000
Treasury stock shares purchased	$ (239)		$ (239)	$ (1,281)
Share-based compensation plans and other (in shares)	(5,000,000)	(5,000,000)	(6,000,000)	(6,000,000)
Share-based compensation plans and other	$ 279	$ 311	$ 344	$ 381
Shares, ending balance (in shares)	1,044,000,000	1,048,000,000	1,044,000,000	1,048,000,000
Equity, ending balance	$ (56,682)	$ (56,850)	$ (56,682)	$ (56,850)
Non- controlling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning balance	94	95	87	94
Spin-off of Organon & Co.	(1)		(1)
Distributions attributable to noncontrolling interests		(1)
Net income (loss) attributable to noncontrolling interests	1	8	8	8
Equity, ending balance	$ 94	$ 102	$ 94	$ 102

Pension and Other Postretirem_3

Pension and Other Postretirement Benefit Plans (Details) - USD ($) $ in Millions	Jun. 02, 2021	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation, Divestiture	$ 99
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Remeasurement due to Settlement	$ 1,700
Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 13	$ 13	$ 26	$ 26
Interest cost		11	14	22	29
Expected return on plan assets		(20)	(19)	(39)	(37)
Amortization of unrecognized prior service credit		(25)	(22)	(50)	(45)
Termination benefits		37	0	37	0
Curtailments		(27)	0	(28)	(1)
Net periodic benefit cost		(11)	(14)	(32)	(28)
U.S. | Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost		98	88	198	175
Interest cost		106	109	202	217
Expected return on plan assets		(191)	(195)	(379)	(388)
Amortization of unrecognized prior service credit		(11)	(12)	(20)	(25)
Net loss amortization		58	76	142	152
Termination benefits		52	1	53	4
Curtailments		9	0	16	2
Settlements		0	9	0	9
Net periodic benefit cost		121	76	212	146
International | Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost		87	73	179	146
Interest cost		30	33	59	68
Expected return on plan assets		(104)	(101)	(209)	(205)
Amortization of unrecognized prior service credit		(4)	(3)	(9)	(6)
Net loss amortization		38	31	78	62
Termination benefits		2	0	3	1
Curtailments		(27)	0	(27)	(1)
Settlements		2	2	2	2
Net periodic benefit cost		$ 24	$ 35	$ 76	$ 67

Other (Income) Expense, Net (De

Other (Income) Expense, Net (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Component of Other Income / Expense of Nonoperating [Line Items]
Interest income		$ (9)	$ (14)	$ (20)	$ (39)
Interest expense		202	209	401	421
Exchange losses		114	24	155	78
Income from investments in equity securities, net		(280)	(551)	(854)	(603)
Net periodic defined benefit plan (credit) cost other than service cost		(110)	(80)	(199)	(170)
Other, net		(20)	25	(41)	(12)
Other (income) expense, net		(103)	(387)	(558)	(325)
Unrealized net losses (gains)		$ (18)	$ 464	$ (199)	$ 469
Forecast
Component of Other Income / Expense of Nonoperating [Line Items]
Unrealized net losses (gains)	$ 380

Other (Income) Expense, Net Oth

Other (Income) Expense, Net Other (Income) Expense, Net - Narrative (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Component of Other Income / Expense of Nonoperating [Line Items]
Interest paid	$ 363	$ 387

Taxes on Income (Details)

Taxes on Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Tax Examination [Line Items]
Effective income tax rate (as percent)	29.30%	14.40%	15.80%	15.60%
Internal Revenue Service (IRS) | Domestic Tax Authority
Income Tax Examination [Line Items]
Tax benefit recognized related to settlement			$ 236
Income taxes paid			190
Internal Revenue Service (IRS) | Domestic Tax Authority | Continuing Operations
Income Tax Examination [Line Items]
Tax benefit recognized related to settlement			207
Income taxes paid			172
Internal Revenue Service (IRS) | Domestic Tax Authority | Discontinued Operations
Income Tax Examination [Line Items]
Tax benefit recognized related to settlement			29
Income taxes paid			$ 18

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share [Abstract]
Net Income from Continuing Operations Attributable to Merck & Co., Inc.	$ 1,213	$ 2,341	$ 3,958	$ 4,812
Income from Discontinued Operations, Net of Taxes and Amounts Attributable to Noncontrolling Interests	332	661	766	1,409
Net income attributable to Merck & Co., Inc.	$ 1,545	$ 3,002	$ 4,724	$ 6,221
Average common shares outstanding	2,533	2,527	2,532	2,531
Common shares issuable	7	9	8	11
Average common shares outstanding assuming dilution	2,540	2,536	2,540	2,542
Basic Earnings per Common Share Attributable to Merck & Co., Inc. Common Shareholders:
Income from Continuing Operations	$ 0.48	$ 0.93	$ 1.56	$ 1.90
Income from Discontinued Operations	0.13	0.26	0.30	0.56
Net Income	0.61	1.19	1.87	2.46
Earnings per Common Share Assuming Dilution Attributable to Merck & Co., Inc. Common Shareholders:
Income from Continuing Operations	0.48	0.92	1.56	1.89
Income from Discontinued Operations	0.13	0.26	0.30	0.55
Net Income	$ 0.61	$ 1.18	$ 1.86	$ 2.45
Common shares issuable under share-based compensation plans excluded from diluted earnings per common share because the effect would have been antidilutive (in shares)	12	8	11	4

Other Comprehensive Income (L_3

Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Equity, beginning balance	$ 27,039	$ 26,300	$ 25,404	$ 26,001
Other comprehensive income (loss) before reclassification adjustments, pretax	1,848	(68)	1,813	(220)
Tax	(395)	45	(522)	2
Other comprehensive income (loss) before reclassification adjustments, net of taxes	1,453	(23)	1,291	(218)
Reclassification adjustments, pretax	126	27	324	28
Tax	(34)	(6)	(58)	(10)
Reclassification adjustments, net of taxes	92	21	266	18
Other comprehensive income (loss), net of taxes	1,545	(2)	1,557	(200)
Spin-off of Organon & Co.	5,091		5,091
Equity, ending balance	33,388	27,744	33,388	27,744
Derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Equity, beginning balance	(36)	135	(266)	31
Other comprehensive income (loss) before reclassification adjustments, pretax	(59)	(110)	121	68
Tax	13	23	(25)	(14)
Other comprehensive income (loss) before reclassification adjustments, net of taxes	(46)	(87)	96	54
Reclassification adjustments, pretax	71	(42)	182	(89)
Tax	(15)	9	(38)	19
Reclassification adjustments, net of taxes	56	(33)	144	(70)
Other comprehensive income (loss), net of taxes	10	(120)	240	(16)
Spin-off of Organon & Co.	0		0
Equity, ending balance	(26)	15	(26)	15
Investments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Equity, beginning balance	0	0	0	18
Other comprehensive income (loss) before reclassification adjustments, pretax	0	0	0	3
Tax	0	0	0	0
Other comprehensive income (loss) before reclassification adjustments, net of taxes	0	0	0	3
Reclassification adjustments, pretax	0	0	0	(21)
Tax	0	0	0	0
Reclassification adjustments, net of taxes	0	0	0	(21)
Other comprehensive income (loss), net of taxes	0	0	0	(18)
Spin-off of Organon & Co.	0		0
Equity, ending balance	0	0	0	0
Employee Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Equity, beginning balance	(4,459)	(4,201)	(4,540)	(4,261)
Other comprehensive income (loss) before reclassification adjustments, pretax	1,767	(21)	1,763	(21)
Tax	(400)	6	(401)	11
Other comprehensive income (loss) before reclassification adjustments, net of taxes	1,367	(15)	1,362	(10)
Reclassification adjustments, pretax	55	69	142	138
Tax	(19)	(15)	(20)	(29)
Reclassification adjustments, net of taxes	36	54	122	109
Other comprehensive income (loss), net of taxes	1,403	39	1,484	99
Spin-off of Organon & Co.	28		28
Equity, ending balance	(3,028)	(4,162)	(3,028)	(4,162)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Equity, beginning balance	(2,127)	(2,325)	(1,828)	(1,981)
Other comprehensive income (loss) before reclassification adjustments, pretax	140	63	(71)	(270)
Tax	(8)	16	(96)	5
Other comprehensive income (loss) before reclassification adjustments, net of taxes	132	79	(167)	(265)
Reclassification adjustments, pretax	0	0	0	0
Tax	0	0	0	0
Reclassification adjustments, net of taxes	0	0	0	0
Other comprehensive income (loss), net of taxes	132	79	(167)	(265)
Spin-off of Organon & Co.	421		421
Equity, ending balance	(1,574)	(2,246)	(1,574)	(2,246)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Equity, beginning balance	(6,622)	(6,391)	(6,634)	(6,193)
Spin-off of Organon & Co.	449		449
Equity, ending balance	$ (4,628)	$ (6,393)	$ (4,628)	$ (6,393)

Segment Reporting - Narrative (

Segment Reporting - Narrative (Details) $ in Billions	3 Months Ended		6 Months Ended
	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)segment	Jun. 30, 2020USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment			2
Sales discounts | $	$ 3.1	$ 2.6	$ 6	$ 5.4

Segment Reporting - Sales of Co

Segment Reporting - Sales of Company's Products (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Sales	$ 11,402	$ 9,353	$ 22,029	$ 19,641
Operating Segments
Segment Reporting Information [Line Items]
Sales	11,452	9,279	22,108	19,420
Other
Segment Reporting Information [Line Items]
Sales	(50)	74	(79)	221
United States
Segment Reporting Information [Line Items]
Sales	5,100	4,322	9,890	9,053
United States | Operating Segments
Segment Reporting Information [Line Items]
Sales	5,106	4,300	9,837	9,015
United States | Other
Segment Reporting Information [Line Items]
Sales	(6)	22	53	38
International
Segment Reporting Information [Line Items]
Sales	6,301	5,031	12,139	10,588
International | Operating Segments
Segment Reporting Information [Line Items]
Sales	6,345	4,979	12,271	10,406
International | Other
Segment Reporting Information [Line Items]
Sales	(44)	52	(132)	182
Total Pharmaceutical segment sales | Operating Segments
Segment Reporting Information [Line Items]
Sales	9,980	8,178	19,218	17,083
Total Pharmaceutical segment sales | Operating Segments | Keytruda
Segment Reporting Information [Line Items]
Sales	4,176	3,388	8,076	6,672
Total Pharmaceutical segment sales | Operating Segments | Alliance revenue - Lynparza (1)
Segment Reporting Information [Line Items]
Sales	248	178	475	323
Total Pharmaceutical segment sales | Operating Segments | Alliance revenue - Lenvima (1)
Segment Reporting Information [Line Items]
Sales	181	151	310	279
Total Pharmaceutical segment sales | Operating Segments | Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	1,234	656	2,151	1,753
Total Pharmaceutical segment sales | Operating Segments | ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	516	378	965	813
Total Pharmaceutical segment sales | Operating Segments | RotaTeq
Segment Reporting Information [Line Items]
Sales	208	168	366	391
Total Pharmaceutical segment sales | Operating Segments | Pneumovax 23
Segment Reporting Information [Line Items]
Sales	152	117	323	373
Total Pharmaceutical segment sales | Operating Segments | Vaqta
Segment Reporting Information [Line Items]
Sales	56	28	90	88
Total Pharmaceutical segment sales | Operating Segments | Bridion
Segment Reporting Information [Line Items]
Sales	387	224	727	524
Total Pharmaceutical segment sales | Operating Segments | Prevymis
Segment Reporting Information [Line Items]
Sales	93	63	174	123
Total Pharmaceutical segment sales | Operating Segments | Noxafil
Segment Reporting Information [Line Items]
Sales	66	73	133	168
Total Pharmaceutical segment sales | Operating Segments | Primaxin
Segment Reporting Information [Line Items]
Sales	60	64	125	115
Total Pharmaceutical segment sales | Operating Segments | Cancidas
Segment Reporting Information [Line Items]
Sales	54	43	111	98
Total Pharmaceutical segment sales | Operating Segments | Invanz
Segment Reporting Information [Line Items]
Sales	48	43	104	108
Total Pharmaceutical segment sales | Operating Segments | Zerbaxa
Segment Reporting Information [Line Items]
Sales	(1)	32	(9)	69
Total Pharmaceutical segment sales | Operating Segments | Simponi
Segment Reporting Information [Line Items]
Sales	202	191	416	406
Total Pharmaceutical segment sales | Operating Segments | Remicade
Segment Reporting Information [Line Items]
Sales	75	73	160	160
Total Pharmaceutical segment sales | Operating Segments | Belsomra
Segment Reporting Information [Line Items]
Sales	78	84	157	163
Total Pharmaceutical segment sales | Operating Segments | Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	192	196	401	441
Total Pharmaceutical segment sales | Operating Segments | Alliance revenue-Adempas/Verquvo (2)
Segment Reporting Information [Line Items]
Sales	74	79	149	133
Total Pharmaceutical segment sales | Operating Segments | Adempas
Segment Reporting Information [Line Items]
Sales	74	57	129	113
Total Pharmaceutical segment sales | Operating Segments | Januvia
Segment Reporting Information [Line Items]
Sales	784	854	1,593	1,628
Total Pharmaceutical segment sales | Operating Segments | Janumet
Segment Reporting Information [Line Items]
Sales	477	490	962	993
Total Pharmaceutical segment sales | Operating Segments | Other pharmaceutical (3)
Segment Reporting Information [Line Items]
Sales	546	548	1,130	1,149
Total Pharmaceutical segment sales | United States | Operating Segments
Segment Reporting Information [Line Items]
Sales	4,647	3,958	8,941	8,266
Total Pharmaceutical segment sales | United States | Operating Segments | Keytruda
Segment Reporting Information [Line Items]
Sales	2,347	2,043	4,528	3,949
Total Pharmaceutical segment sales | United States | Operating Segments | Alliance revenue - Lynparza (1)
Segment Reporting Information [Line Items]
Sales	124	105	242	190
Total Pharmaceutical segment sales | United States | Operating Segments | Alliance revenue - Lenvima (1)
Segment Reporting Information [Line Items]
Sales	88	98	173	188
Total Pharmaceutical segment sales | United States | Operating Segments | Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	454	168	766	629
Total Pharmaceutical segment sales | United States | Operating Segments | ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	386	263	718	596
Total Pharmaceutical segment sales | United States | Operating Segments | RotaTeq
Segment Reporting Information [Line Items]
Sales	111	100	229	241
Total Pharmaceutical segment sales | United States | Operating Segments | Pneumovax 23
Segment Reporting Information [Line Items]
Sales	100	21	173	203
Total Pharmaceutical segment sales | United States | Operating Segments | Vaqta
Segment Reporting Information [Line Items]
Sales	22	17	47	47
Total Pharmaceutical segment sales | United States | Operating Segments | Bridion
Segment Reporting Information [Line Items]
Sales	197	107	364	250
Total Pharmaceutical segment sales | United States | Operating Segments | Prevymis
Segment Reporting Information [Line Items]
Sales	37	28	72	55
Total Pharmaceutical segment sales | United States | Operating Segments | Noxafil
Segment Reporting Information [Line Items]
Sales	14	6	29	14
Total Pharmaceutical segment sales | United States | Operating Segments | Primaxin
Segment Reporting Information [Line Items]
Sales	0	1	0	1
Total Pharmaceutical segment sales | United States | Operating Segments | Cancidas
Segment Reporting Information [Line Items]
Sales	1	(2)	3	1
Total Pharmaceutical segment sales | United States | Operating Segments | Invanz
Segment Reporting Information [Line Items]
Sales	(4)	0	0	6
Total Pharmaceutical segment sales | United States | Operating Segments | Zerbaxa
Segment Reporting Information [Line Items]
Sales	(2)	17	(4)	37
Total Pharmaceutical segment sales | United States | Operating Segments | Simponi
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Total Pharmaceutical segment sales | United States | Operating Segments | Remicade
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Total Pharmaceutical segment sales | United States | Operating Segments | Belsomra
Segment Reporting Information [Line Items]
Sales	14	22	32	49
Total Pharmaceutical segment sales | United States | Operating Segments | Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	74	76	145	151
Total Pharmaceutical segment sales | United States | Operating Segments | Alliance revenue-Adempas/Verquvo (2)
Segment Reporting Information [Line Items]
Sales	81	73	149	122
Total Pharmaceutical segment sales | United States | Operating Segments | Adempas
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Total Pharmaceutical segment sales | United States | Operating Segments | Januvia
Segment Reporting Information [Line Items]
Sales	284	413	632	768
Total Pharmaceutical segment sales | United States | Operating Segments | Janumet
Segment Reporting Information [Line Items]
Sales	74	143	158	256
Total Pharmaceutical segment sales | United States | Operating Segments | Other pharmaceutical (3)
Segment Reporting Information [Line Items]
Sales	245	259	485	513
Total Pharmaceutical segment sales | International | Operating Segments
Segment Reporting Information [Line Items]
Sales	5,333	4,220	10,277	8,818
Total Pharmaceutical segment sales | International | Operating Segments | Keytruda
Segment Reporting Information [Line Items]
Sales	1,829	1,345	3,548	2,722
Total Pharmaceutical segment sales | International | Operating Segments | Alliance revenue - Lynparza (1)
Segment Reporting Information [Line Items]
Sales	124	73	233	133
Total Pharmaceutical segment sales | International | Operating Segments | Alliance revenue - Lenvima (1)
Segment Reporting Information [Line Items]
Sales	93	53	137	91
Total Pharmaceutical segment sales | International | Operating Segments | Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	781	488	1,385	1,124
Total Pharmaceutical segment sales | International | Operating Segments | ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	130	115	246	217
Total Pharmaceutical segment sales | International | Operating Segments | RotaTeq
Segment Reporting Information [Line Items]
Sales	97	68	137	150
Total Pharmaceutical segment sales | International | Operating Segments | Pneumovax 23
Segment Reporting Information [Line Items]
Sales	52	96	150	170
Total Pharmaceutical segment sales | International | Operating Segments | Vaqta
Segment Reporting Information [Line Items]
Sales	34	11	43	41
Total Pharmaceutical segment sales | International | Operating Segments | Bridion
Segment Reporting Information [Line Items]
Sales	190	117	363	274
Total Pharmaceutical segment sales | International | Operating Segments | Prevymis
Segment Reporting Information [Line Items]
Sales	56	35	103	68
Total Pharmaceutical segment sales | International | Operating Segments | Noxafil
Segment Reporting Information [Line Items]
Sales	52	67	104	154
Total Pharmaceutical segment sales | International | Operating Segments | Primaxin
Segment Reporting Information [Line Items]
Sales	60	63	125	114
Total Pharmaceutical segment sales | International | Operating Segments | Cancidas
Segment Reporting Information [Line Items]
Sales	53	45	108	98
Total Pharmaceutical segment sales | International | Operating Segments | Invanz
Segment Reporting Information [Line Items]
Sales	52	43	104	102
Total Pharmaceutical segment sales | International | Operating Segments | Zerbaxa
Segment Reporting Information [Line Items]
Sales	1	15	(5)	32
Total Pharmaceutical segment sales | International | Operating Segments | Simponi
Segment Reporting Information [Line Items]
Sales	202	191	416	406
Total Pharmaceutical segment sales | International | Operating Segments | Remicade
Segment Reporting Information [Line Items]
Sales	75	73	160	160
Total Pharmaceutical segment sales | International | Operating Segments | Belsomra
Segment Reporting Information [Line Items]
Sales	63	61	125	114
Total Pharmaceutical segment sales | International | Operating Segments | Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	118	120	256	290
Total Pharmaceutical segment sales | International | Operating Segments | Alliance revenue-Adempas/Verquvo (2)
Segment Reporting Information [Line Items]
Sales	(7)	6	0	11
Total Pharmaceutical segment sales | International | Operating Segments | Adempas
Segment Reporting Information [Line Items]
Sales	74	57	129	113
Total Pharmaceutical segment sales | International | Operating Segments | Januvia
Segment Reporting Information [Line Items]
Sales	500	441	961	860
Total Pharmaceutical segment sales | International | Operating Segments | Janumet
Segment Reporting Information [Line Items]
Sales	403	348	805	737
Total Pharmaceutical segment sales | International | Operating Segments | Other pharmaceutical (3)
Segment Reporting Information [Line Items]
Sales	301	289	644	637
Total Animal Health segment sales | Operating Segments
Segment Reporting Information [Line Items]
Sales	1,472	1,101	2,890	2,314
Total Animal Health segment sales | Operating Segments | Livestock
Segment Reporting Information [Line Items]
Sales	821	648	1,640	1,386
Total Animal Health segment sales | Operating Segments | Companion Animals
Segment Reporting Information [Line Items]
Sales	651	453	1,250	928
Total Animal Health segment sales | United States | Operating Segments
Segment Reporting Information [Line Items]
Sales	459	342	896	726
Total Animal Health segment sales | United States | Operating Segments | Livestock
Segment Reporting Information [Line Items]
Sales	161	122	318	284
Total Animal Health segment sales | United States | Operating Segments | Companion Animals
Segment Reporting Information [Line Items]
Sales	298	220	578	442
Total Animal Health segment sales | International | Operating Segments
Segment Reporting Information [Line Items]
Sales	1,012	759	1,994	1,588
Total Animal Health segment sales | International | Operating Segments | Livestock
Segment Reporting Information [Line Items]
Sales	659	526	1,322	1,102
Total Animal Health segment sales | International | Operating Segments | Companion Animals
Segment Reporting Information [Line Items]
Sales	353	233	672	486
Other segment sales (4) | Operating Segments
Segment Reporting Information [Line Items]
Sales	0	0	0	23
Other segment sales (4) | United States | Operating Segments
Segment Reporting Information [Line Items]
Sales	0	0	0	23
Other segment sales (4) | International | Operating Segments
Segment Reporting Information [Line Items]
Sales	$ 0	$ 0	$ 0	$ 0

Segment Reporting - Revenues by

Segment Reporting - Revenues by Geographic Area (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue from External Customer [Line Items]
Sales	$ 11,402	$ 9,353	$ 22,029	$ 19,641
United States
Revenue from External Customer [Line Items]
Sales	5,100	4,322	9,890	9,053
Europe, Middle East and Africa
Revenue from External Customer [Line Items]
Sales	3,333	2,622	6,569	5,591
China
Revenue from External Customer [Line Items]
Sales	975	623	1,697	1,269
Japan
Revenue from External Customer [Line Items]
Sales	661	621	1,291	1,204
Asia Pacific (other than China and Japan)
Revenue from External Customer [Line Items]
Sales	594	489	1,168	1,015
Latin America
Revenue from External Customer [Line Items]
Sales	532	423	1,032	875
Other
Revenue from External Customer [Line Items]
Sales	$ 207	$ 253	$ 382	$ 634

Segment Reporting - Profits to

Segment Reporting - Profits to Income Before Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Profits	$ 1,717	$ 2,741	$ 4,704	$ 5,702
Interest income	9	14	20	39
Interest expense	(202)	(209)	(401)	(421)
Amortization			871	988
Research and development	(4,321)	(2,085)	(6,732)	(4,260)
Restructuring costs	(82)	(82)	(380)	(152)
Total segment profits
Segment Reporting Information [Line Items]
Profits	7,809	6,240	14,969	13,098
Total segment profits | Pharmaceutical segment
Segment Reporting Information [Line Items]
Profits	7,257	5,832	13,845	12,209
Total segment profits | Animal Health segment
Segment Reporting Information [Line Items]
Profits	552	408	1,124	887
Total segment profits | Other segment
Segment Reporting Information [Line Items]
Profits	0	0	0	2
Other profits
Segment Reporting Information [Line Items]
Profits	(79)	43	(113)	163
Unallocated
Segment Reporting Information [Line Items]
Interest income	9	14	20	39
Interest expense	(202)	(209)	(401)	(421)
Amortization	357	599	871	988
Depreciation	(332)	(367)	(673)	(733)
Research and development	(4,175)	(1,956)	(6,480)	(4,020)
Restructuring costs	(82)	(82)	(380)	(152)
Other unallocated, net	$ (874)	$ (343)	$ (1,367)	$ (1,284)